Every team improves its processes eventually. The question is whether the improvement is deliberate, measured and kept, or whether it happens by accident, gets lost when the person who made it leaves, and has to be rediscovered by the next team eighteen months later.
Continuous improvement is the discipline of making small, frequent, measured changes to how work is done, keeping the ones that help and discarding the ones that do not. It sits underneath most of the well-known operations frameworks, from the Deming cycle to kaizen, Lean and Six Sigma, and it is the mechanism by which a good process stays good after the people who designed it have moved on.
This guide is for operations, IT, HR and team leads at companies of 10 to 500 people who have some processes documented, suspect several of them are slower or more error-prone than they need to be, and want a method for fixing that which does not depend on a consultant or a six-month transformation programme. By the end you will be able to choose an improvement model that suits your team, run one improvement loop end to end, put the numbers in place to know whether it worked, and build the habits that make the second and tenth loops easier than the first.
What Is Continuous Improvement?
The formal definition is an ongoing effort to improve products, services or processes through incremental changes over time. The practical definition is more useful: continuous improvement is a loop. Look at how a process performs today, change one thing, measure whether the change helped, and either make it the new standard or undo it. Then go round again.
Three words in that loop carry the weight. One thing, because changing five things at once tells you nothing about which of them worked. Measure, because an improvement that feels better but does not move a number is an opinion. And standard, because an improvement that is not written into the process is a personal habit that leaves with the person who has it. That last point is why continuous improvement depends on process standardization having happened first: you cannot improve from a baseline you do not have.
Continuous improvement is not the same as fixing things when they break. Fixing a broken process is maintenance, and every team does it. Continuous improvement is applied to processes that are working, on the assumption that working is not the same as working as well as they could. It is also not the same as a transformation programme. A programme has a start, an end and a budget. Continuous improvement is meant to be a permanent feature of how the team operates, which is why building the culture around it matters as much as choosing the model.
Where the idea comes from
The modern practice traces to statistical quality control work in the 1920s and 30s at Bell Labs, where Walter Shewhart developed the cycle that W. Edwards Deming later taught to Japanese industry after the Second World War. Toyota built it into the heart of its production system as kaizen, literally "change for the better", and Masaaki Imai's 1986 book of that name brought the term to Western management. Every model in this guide is a variation on Shewhart's original loop.
Incremental vs Breakthrough Improvement
Improvements come in two sizes, and confusing them is the source of a lot of wasted effort. Incremental improvement, which Toyota calls kaizen, changes one step, one form, one handoff. Breakthrough improvement, kaikaku in the same vocabulary, redesigns the process from scratch. Business process reengineering, the approach Michael Hammer set out in 1990 with the instruction to obliterate rather than automate, is breakthrough improvement in its most aggressive form.
| Incremental (kaizen) | Breakthrough (kaikaku, BPR) | |
|---|---|---|
| Scope of change | One step, one handoff, one form field | The whole process, sometimes the whole function |
| Who decides | The people doing the work, often on the spot | Leadership, with a project team |
| Frequency | Weekly or continuous | Every few years, or when the process is clearly broken |
| Cost and risk | Low, and easily reversed | High, and hard to reverse |
| Typical gain per change | Small, but compounding | Large, if it works |
| Disruption | Minimal | Significant, with a dip before the gain |
| Use when | The process is basically sound and stable | The process is fundamentally wrong for the current business |
The legacy version of this article offered a useful test for deciding which kind of change you are looking at. Ask two questions: if someone else were making this change, would you expect them to talk to the team first? And could it cause confusion or problems for anyone else who runs the process? If the answer to both is no, make the change, record it, and mention it at the next review. If the answer to either is yes, it needs the people who run the process in the room before it happens.
Most teams need both kinds, in a specific ratio: a great deal of incremental improvement, and a breakthrough every few years when the incremental changes have stopped paying off or the business has changed around the process. An onboarding process that has been refined weekly for two years may still need rebuilding when the company opens a second office in another country. Our guide to business process reengineering covers the breakthrough end; this guide is mostly about the incremental end, because that is where most teams get most of their gain.
The Continuous Improvement Models and When to Use Each
The models below share the same loop and differ in emphasis, vocabulary and the amount of statistical machinery. You do not need to adopt one wholesale. Most teams that do this well borrow the loop from PDCA, the culture from kaizen, the waste categories from Lean, the root-cause tools from Six Sigma, and the focus from Theory of Constraints.
PDCA (the Deming cycle)
Plan, Do, Check, Act. Plan a change and predict its effect. Do it, on a small scale. Check the result against the prediction. Act: adopt the change as the new standard if it worked, abandon it if it did not, and in either case start the next cycle. Deming later preferred "Study" to "Check" to stress that the point is to learn, not to tick a box, and the variant is usually written PDSA.
Use it when: you need a lightweight structure that any team can follow without training. PDCA is the default for teams new to continuous improvement, and the seven-step loop later in this guide is a PDCA cycle with the steps spelt out.
Kaizen
Kaizen is less a method than a stance: everyone, every day, looks for small things to improve in their own work, and the organisation makes it easy to act on what they find. In its Toyota form it includes suggestion systems, short daily improvement discussions, and kaizen events, which are focused two-to-five-day workshops that take one process apart and put it back together better.
Use it when: you want improvement to come from the people doing the work rather than from a central team. Kaizen is the right model for a support desk, a warehouse or an HR operations team where the practitioners see the problems long before management does. It fails when management asks for suggestions and then does nothing with them.
Lean
Lean, as codified by Womack and Jones in Lean Thinking, is built on five principles: specify value from the customer's point of view, map the value stream, make the work flow, let the customer pull, and pursue perfection. Its distinctive contribution to continuous improvement is a taxonomy of waste, the seven or eight categories of activity that consume effort without adding value, which gives a team a shared vocabulary for what to remove.
Use it when: the process has obvious waiting, handoffs, rework or overproduction. Lean's value stream mapping is the fastest way to see where time goes in a multi-team process. Our guide to lean manufacturing principles covers the origins; the principles transfer to office work with surprisingly little adjustment.
Six Sigma and DMAIC
Six Sigma, developed at Motorola in the 1980s, treats improvement as a statistical problem: reduce variation until defects are vanishingly rare. Its improvement loop is DMAIC: Define the problem and the customer requirement, Measure current performance, Analyse the data for root causes, Improve by testing and implementing solutions, Control by putting the gains into the standard and monitoring them.
Use it when: the process runs at volume, the defect is measurable and the cause is not obvious. A manufacturing line, a claims-processing team or a high-volume support desk can justify the measurement discipline. A ten-person team improving its monthly reporting process usually cannot, and will find the machinery gets in the way. Our manufacturing quality control checklist shows the Control phase in practice.
Theory of Constraints
Eliyahu Goldratt's Theory of Constraints, set out in The Goal, starts from the observation that every process has one bottleneck that limits its throughput, and that improving anything other than the bottleneck does not improve the process. Its five focusing steps are: identify the constraint, exploit it (get the most out of it as it is), subordinate everything else to it, elevate it (invest to increase its capacity), and then, once it is no longer the constraint, find the new one.
Use it when: the team is making improvements that do not seem to move the overall result. A support desk that speeds up first response but still has a five-day resolution time has been improving a non-constraint. Theory of Constraints tells you to find the step where the queue forms and work on that.
Choosing in practice
Start with PDCA for the loop and Theory of Constraints for deciding where to point it. Add Lean's waste categories when you need to explain what you are removing, and Six Sigma's measurement discipline only for high-volume processes where the cause is genuinely hidden. Adopt the kaizen stance from day one, because without it the other four are management projects rather than a way of working.
A Worked Example: Cutting IT Support Resolution Time
The following is a composite drawn from the kind of improvement loops IT teams run regularly, simplified enough to follow in one sitting. The numbers are illustrative rather than from a published study; the shape of the problem is very common.
An internal IT support team of six engineers at a 250-person company handles around 500 tickets a month. Median time to resolution is three and a half working days. Users complain that tickets sit for days; engineers complain that users never give them the information they need. The team lead has been asked to improve it and has been told, without further detail, to "look at automation".
Baseline
Before changing anything, the lead pulls three months of ticket data and looks at where the time goes. Resolution time splits into three states: waiting for an engineer to pick the ticket up (median four hours), engineer working (median three hours across the life of the ticket) and waiting for the user to respond (median two days). The bottleneck is not the engineers. It is the round trips to the user.
Root cause
Five whys on a sample of long-running tickets: why did this ticket wait two days? Because the engineer asked the user which device they were on. Why did they have to ask? Because the ticket did not say. Why not? Because the request form has a free-text box and nothing else. Why is that? Because the form was set up in an afternoon three years ago. Why has nobody changed it? Because nobody owns the form. A fishbone diagram would have arrived at the same place with more ceremony; for a problem this size, five whys is enough.
One change
The team standardises the first-response step. Every ticket, on pickup, is triaged with a short checklist that requires the engineer to confirm four things before doing anything else: device, operating system, whether the issue is reproducible, and the last time it worked. If any are missing, a single templated message asks for all of them at once. The team resists the temptation to also rebuild the request form, change the SLA and buy a chatbot in the same month.
Measure
After four weeks: median waiting-for-user time falls from two days to under one, because one round trip replaces two or three. Median resolution falls from three and a half days to just over two. Engineer working time is unchanged, which is what you would expect, since the engineers were never the problem. The improvement is written into the standard support ticket response checklist and the team lead picks the next constraint, which is now the four-hour pickup delay.
Three things to notice. The loop began with measurement, not with an idea. It changed one step, so the result was attributable. And the change was to a human step, captured in a checklist, not an automation, even though automation was the initial brief. Automating the old form would have produced the same missing information faster.
Run Your First Improvement Loop From a Template
CheckFlow's template library includes a continuous improvement cycle checklist, plus standard processes for IT, HR, finance and operations that give you a baseline to improve from. Copy one and have it running today.
Browse Free TemplatesThe Improvement Loop in Practice: 7 Steps
This is the loop from the worked example, generalised. It is a PDCA cycle with the steps made explicit enough to hand to a team lead who has never run one. Budget four to six weeks for one loop on a process of moderate complexity, most of which is waiting for enough runs to measure.
Establish the baseline
Before you change anything, find out how the process performs now. If it runs as a tracked checklist, this is a report: completion rate, cycle time per run and per step, error or rework rate, over the last 90 days. If it runs from documents and memory, you will need to sample recent runs by hand, and the absence of data is your first finding. A baseline you cannot measure is a process you should standardise before you try to improve.
Choose one process, and one problem within it
Pick a process that runs often enough to give you data within a month and matters enough that people will notice the improvement. Then narrow to one problem: not "onboarding is slow" but "new starters wait an average of three days for system access". Use Theory of Constraints here: find the step where the queue forms, because improving any other step will not change the overall result. Resist the impulse to run three loops at once. The second loop starts when the first one finishes.
Measure the problem precisely
Define the one number that describes the problem, how you will collect it, and what "improved" means before you decide what to change. "Median waiting-for-user time, from the ticket data, target under one day" is a measurement. "Users are happier" is not. Write down the current value and the target. This is the step that separates continuous improvement from having opinions about a process.
Find the root cause
Use five whys for simple problems: ask why the problem occurs, then why that occurs, until you reach something the team controls. Use a fishbone (Ishikawa) diagram for messier ones, grouping candidate causes under people, process, systems, materials, environment and measurement, then testing the likely ones against the data. The test of a root cause is that fixing it would prevent the problem, not just the instance. "The engineer forgot" is never a root cause; "the process depends on the engineer remembering" might be.
Make one small change and run it
Design the smallest change that addresses the root cause, predict its effect on your number, and run it for enough cycles to see the result. A step reordered, a required field added, a handoff removed, a template message introduced. Small is deliberate: a small change is cheap to reverse if the prediction is wrong, and its effect is attributable. Keep a note of what you changed and when, so the before-and-after comparison is honest.
Standardise the winner
If the number moved as predicted, write the change into the process so that every future run includes it. Update the template, bump the version, and tell the people who run it what changed and why. If the number did not move, reverse the change and record what you learnt; a disproved hypothesis is a result too. The most common failure of continuous improvement programmes is not bad ideas but good ideas that were tried, worked, and were never made permanent. This is where our guides to writing standard operating procedures and creating checklists come in.
Repeat, on the new constraint
Once the change is standard, the bottleneck has moved. Go back to the baseline data, find the new longest wait or most frequent error, and start again. Put the next loop in the calendar rather than waiting for enthusiasm; a team that runs one loop a month will have improved its most important process twelve times in a year, which no transformation programme would promise.
Building a Continuous Improvement Culture
A single improvement loop can be run by one determined team lead. Continuous improvement, the permanent kind, needs the team to want to do it, which is a question of culture. Four things make the difference between a team that improves and a team that was once told to.
Psychological safety
Improvement starts with someone saying "this step is a waste of time" or "I made a mistake here and I think the process made it likely". Neither will be said in a team where problems are treated as personal failures. The practical version of psychological safety is that when a process fails, the first question is what in the process allowed it, not who did it. Amy Edmondson's research on teams in hospitals found that the units reporting the most errors were not the worst performers but the ones where staff felt safe to report, which is exactly the property an improvement culture needs.
A suggestion system that visibly acts
Toyota's suggestion system is famous for the volume of ideas it receives, but the volume is a consequence of something else: the ideas are acted on, quickly, and the person who suggested them can see the result. Most corporate suggestion schemes fail on that second half. If you ask a team for improvement ideas, commit to a response on every one within two weeks, and make a visible list of the ones that were adopted. A suggestion that disappears into a spreadsheet teaches the team not to make the next one.
Retrospectives with a follow-through owner
Software teams borrowed the retrospective from agile, and it transfers to any process: after each cycle, or each month, spend 30 minutes on what went well, what did not, and what one thing to change. The part most teams get wrong is the last step. A retrospective that produces a list of eight actions with no owners produces nothing. Pick one, assign it, and check it at the start of the next retrospective. Our sprint planning checklist shows how the retrospective feeds the next planning cycle.
Visible wins
Improvement is invisible by default: the ticket that did not bounce, the onboarding that did not stall, the error that did not happen. Make it visible. A simple chart of the target number over time, on a wall or a dashboard, does more for a culture of improvement than any amount of training. When the team can see the resolution time falling month by month, the next loop needs no selling.
Culture also needs the organisation to be clear about who is responsible. The lead for continuous improvement does not need to be a dedicated role, but it does need to be somebody's named job, whether that is the operations manager or a team lead with a day a month ring-fenced for it. Our guide to what operations management is covers where improvement sits in that role.
Continuous Improvement Metrics
There are two families of metrics: those that tell you whether a specific improvement worked, and those that tell you whether the improvement programme itself is alive. Teams usually track the first and forget the second.
Process metrics: did this change work?
Cycle time is the elapsed time from trigger to completion, and its spread matters more than its average. Improvements often show up first as the slow outliers disappearing. Track it per step as well as per run, because the step with the longest wait is the next constraint.
First-time-right rate, or its inverse, the rework rate, is the proportion of runs completed without having to be reopened or corrected. For onboarding, it is starters who had everything on day one. For invoice processing, it is invoices paid once, correctly, without a supplier query.
Throughput is runs completed per period with the same resources. If cycle time falls but throughput does not rise, you have improved a step that was not the constraint.
Adherence is the proportion of runs that followed the current standard. It is the control metric: an improvement that is only applied in half the runs will show half the effect, and you will conclude wrongly that it did not work.
Programme metrics: is improvement happening?
Loops completed per quarter, counting only loops that reached step six, standardised or reversed. A team doing one a month is doing well. A team with six loops open and none closed has a follow-through problem.
Time from suggestion to decision, measured for every idea raised. Under two weeks keeps a suggestion system alive. Over a month kills it.
Proportion of improvements originating from practitioners rather than management. A rising share is the best single indicator that kaizen has taken hold.
A note on measuring people
Metrics that measure a process are safe to publish. Metrics that measure individuals inside a process, such as tickets closed per engineer, will be optimised for as soon as they are published, usually at the expense of the thing you actually wanted. Deming was emphatic that most variation comes from the system rather than the individual. Measure the system, and let the people inside it improve it.
If your processes run as tracked checklists, most of the process metrics come out of the completion data automatically, and a reporting dashboard turns the monthly review into a five-minute glance. If they do not, collecting the baseline in step one will be the longest part of every loop, which is a strong argument for standardising first.
Common Continuous Improvement Mistakes
Most continuous improvement programmes that stall do so for one of these reasons. Each is easier to prevent than to recover from.
Mistake 1: Improving before standardising. The team tries to improve a process that is performed differently by everyone who runs it. There is no baseline, so the effect of any change is invisible, and the "improvement" is just one more variant. Standardise first, get adherence above 80%, measure for a month, and then improve. Toyota's rule that there is no kaizen without a standard is not a slogan; it is a description of what the data will look like if you skip the step.
Mistake 2: Too many initiatives at once. Leadership announces a continuous improvement programme and every team launches three projects. Six months later, none is complete, the numbers have moved in ways nobody can attribute, and the programme is quietly dropped. Run one loop per process at a time, and no more loops across the organisation than there are people with time to own them. Finishing three loops beats starting fifteen.
Mistake 3: No owner for the loop. An improvement idea is raised in a meeting, everyone agrees it is good, and it is never mentioned again, because agreeing is not the same as assigning. Every loop, from step one, has one named person responsible for getting it to step six. If nobody can be named, the loop does not start.
Mistake 4: No follow-through into the standard. The change is tried, it works, everyone is pleased, and three months later the process has drifted back because the change lived in one person's habits rather than in the template. Step six is not optional. An improvement is finished when the next person to run the process, who has never heard of the improvement, does it the new way by default.
Mistake 5: Measuring the wrong thing, or nothing. The team improves the step that was easiest to improve rather than the constraint, and reports success on a metric that does not affect the outcome. First-response time falls; resolution time does not; users are no happier. Define the outcome metric before choosing what to change, and check that the step you are improving actually drives it.
Mistake 6: Treating it as a project with an end date. The programme has a launch, a budget and a closing report, after which "continuous" improvement stops. The whole point is that it does not end. Put the next loop in the calendar before the current one is finished, and build the review into the operating rhythm rather than into a project plan.
Checklists as the Vehicle: Every Run Produces Data
Every step in the improvement loop is easier if the process runs as a checklist rather than from a document. This is not a coincidence; it is the reason checklists are the natural vehicle for continuous improvement in teams that do not have a statistics department.
A process run from a document leaves no record of how it went. To establish a baseline you have to interview people and reconstruct runs from email. To measure a change you have to do it again. A process run as a tracked checklist records, for every run, when each step was started and completed, who did it, and what values were captured in the required fields. The baseline is a report. The measurement after the change is the same report, filtered to a later date range. The data collection that consumes most of a manual improvement loop simply does not exist.
The checklist is also the standard itself, which closes the gap at step six. When the improvement is written into the template, every subsequent run includes it automatically, and adherence is visible because runs that skipped the new step show up as incomplete. And because templates are versioned, you can see exactly when the change went in and compare the runs before and after it without arguing about whose memory is right.
There is a subtler benefit. A checklist with required fields turns every practitioner into a data collector without asking them to do anything extra. The engineer who records the backup size, the HR coordinator who records the date the laptop was shipped, the finance assistant who records the invoice approver: each is producing the measurement that the next improvement loop will need. This is what makes recurring checklists so valuable for improvement work: a process that runs weekly on a schedule generates fifty data points a year without anyone deciding to measure it.
- Every run is timestamped per step, so cycle time and waiting time are available without a stopwatch
- Required fields capture the values you will want to compare, at the moment they are known
- Skipped or incomplete steps are visible, so adherence is measured rather than assumed
- The template is the standard, so an improvement written into it applies to every future run
- Template versions mark exactly when each change went in, making before-and-after comparison honest
- Recurring schedules produce a steady stream of comparable runs without anyone remembering to start them
- A dashboard of active runs shows where the queue is forming, which is where the next loop should point
If your improvement work is stalling at the baseline step, the most effective single change is to move the process from a document into checklist software that records each run. Our guide to what business process management is puts this in the wider context of how processes are designed, run and improved together, and our IT change management checklist is a good example of a process that produces exactly the data its own improvement needs.
Free Continuous Improvement Templates
These three templates cover the improvement loop itself, the most common trigger for one (a defect that needs a root cause), and the high-frequency IT process from the worked example. Each runs as a live checklist with assigned steps, required fields and a completion record, so the data for the next loop is collected as the current one runs.
How CheckFlow Fits
CheckFlow is business process management software that runs each of your processes as a template, so the baseline, the change and the measurement all live in one place. Every run of a template is a checklist with each step assigned to a named person or a role, due dates calculated from the trigger, and the values you decide to capture recorded as required fields.
For the baseline and measurement steps, the real-time dashboard shows every active run and where it is waiting, and analytics report cycle time, completion rate and per-step timing across any date range. The worked example's finding that tickets spent most of their life waiting for the user is the kind of thing that dashboard surfaces without a data export.
For the change and standardise steps, template versioning records exactly what changed and when. Runs already in progress finish on the version they started with; new runs use the new one. That gives you a clean before-and-after comparison, and it means an improvement, once written into the template, is applied by every future run whether or not the person doing it has heard about the change. Conditional logic lets you add a branch for the variant you discovered in root-cause analysis without duplicating the whole process.
Recurring schedules keep calendar-driven processes producing comparable runs, which is where most of your measurement data will come from. The audit trail records who completed each step and when, so adherence is measured rather than assumed. Zapier and the API connect CheckFlow to your ticketing, HR and finance systems, so a closed ticket or a signed contract can start the next run, and the automation you add later is applied to a process that is already stable and measured.
Pricing starts from $10 per user per month, with a 14-day free trial and no credit card required. Most teams have their first process running as a tracked checklist, and their baseline data accumulating, within an afternoon.
Give Your Next Improvement Loop a Baseline
Move one process into CheckFlow, let it run for a month, and start your first loop with real cycle-time and adherence data instead of a reconstruction. Free for 14 days, no credit card needed.
Start Your Free TrialFrequently Asked Questions
Continuous improvement is an ongoing effort to improve processes, products or services through small, frequent, measured changes. In practice it is a loop: measure how a process performs now, change one thing, measure whether the change helped, and either write it into the standard or reverse it, then repeat. It applies to processes that are already working, on the assumption that working is not the same as working as well as they could.
The idea underlies most operations frameworks, including the Deming cycle, kaizen, Lean, Six Sigma and Theory of Constraints. It is distinct from fixing broken processes, which is maintenance, and from transformation programmes, which have an end date.
The four stages usually referred to are the PDCA cycle: Plan, Do, Check, Act. Plan a change and predict its effect; do it on a small scale; check the result against the prediction; and act by adopting the change as the new standard if it worked or abandoning it if it did not. Deming later preferred "Study" to "Check", and the variant is written PDSA.
Six Sigma's DMAIC loop spells the same idea out in five stages: Define, Measure, Analyse, Improve, Control. Whichever version you use, the essential elements are a baseline measurement, one change at a time, a comparison against the baseline, and writing the winner into the standard.
Kaizen is the Japanese term, meaning "change for the better", for the approach to continuous improvement developed within the Toyota Production System. It emphasises small, incremental changes made frequently by the people doing the work, supported by suggestion systems and short improvement events. Continuous improvement is the broader English term that covers kaizen along with other models such as PDCA, Lean, Six Sigma and Theory of Constraints.
In everyday use the two are close to synonyms. The useful distinction is that kaizen specifically describes the bottom-up, practitioner-led version, whereas continuous improvement can also describe a management-led programme.
An IT support team finds, from its ticket data, that most resolution time is spent waiting for users to answer questions the engineer should have asked up front. It standardises the first response with a short checklist that requires device, operating system, reproducibility and last-known-good time before any other work starts. After a month, round trips to the user fall from two or three to one, and median resolution time drops by more than a day.
The pattern generalises: HR shortening the time to system access for new starters, finance reducing duplicate supplier payments, or a warehouse cutting the steps between order and dispatch. Each starts with a measured baseline, changes one thing, and writes the result into the standard.
Start with one process, not a programme. Choose a process that runs often enough to produce data within a month and matters enough that people will notice the improvement. Make sure it is standardised and running as a tracked checklist, so you have a baseline. Then run one loop: measure, find the constraint, identify the root cause, make one small change, measure again, and write the winner into the standard.
Give the loop one named owner and put the next loop in the calendar before the first is finished. The programme emerges from the habit, not the other way round. Announcing a company-wide initiative before a single loop has completed is the most reliable way to make continuous improvement fail.
Yes. If a process is performed differently by everyone who runs it, there is no baseline, and the effect of any change is invisible among the existing variation. Toyota's rule that there can be no kaizen without a standard describes exactly what the data looks like when you try: every run is different, so nothing can be attributed to the improvement.
The practical sequence is to agree one method, run it as a tracked checklist until adherence is above about 80%, collect a month or so of baseline data, and then start improving. Standardisation is also what makes step six of the loop possible: an improvement is only permanent when it is written into a standard that every future run follows.
For each process: cycle time (and its spread, per step as well as per run), first-time-right or rework rate, throughput, and adherence to the current standard. Cycle time per step shows you where the constraint is, rework rate is the number that justifies the work financially, and adherence is the control metric that tells you whether an improvement is actually being applied.
For the programme itself: loops completed per quarter, time from suggestion to decision, and the proportion of improvements that originated with practitioners rather than management. Measure the process, not the individuals inside it; a metric attached to a person will be optimised for at the expense of the outcome.