Kaizen Method in Practice – What Is the Aggregation of Marginal Gains?

The Kaizen method is very often reduced to the slogan: “let’s make small improvements.”
Let everyone submit ideas!

Such Kaizen often does not work! The real strength of Kaizen does not lie in the improvements themselves.

Kaizen culture:

Kaizen understood solely as a collection of small ideas is something completely different from a Kaizen culture.

Without it, even the best initiatives quickly lose momentum. Only in an organization that accepts continuous improvement and supports its employees does the aggregation of marginal gains become possible.

This is what allows small changes to add up and, over time, translate into a real operational advantage.

In this article, we will show what the aggregation of marginal gains looks like in practice, how it works in a production environment, and why Kaizen quickly loses its meaning without data, IT tools, and organizational consistency.

The Kaizen philosophy originates from the Japanese approach to production management. It is based on the belief that a process can – and should – be improved every day. This is not about spectacular projects or revolutionary changes. Large changes are simply too big for most employees. Too big means uncertainty and fear. Small ones are safe and easy to implement.

What matters most is employee awareness and everyday work focused on eliminating waste, improving processes, and enhancing standards.

In practice, this means:

The problem arises when Kaizen is treated as a set of loose initiatives rather than a coherent system.

Kaizen does not end with coming up with an improvement idea. Employees have ideas and are creative. The problem is that companies often lack systems to implement them safely and consciously. Employee suggestion systems alone usually do not work as companies – and employees – would like them to. Even small improvement ideas that are not always valuable from a strict business perspective should still be implemented. Not only for profit, but to build employee self-motivation.

For changes to be effective, they must be evaluated based on data. If a solution works, it should be standardized. If not, we quickly revert to the previous state and look for a new improvement – and, importantly, without looking for someone to blame! Change is an experiment, not a dogma. This approach naturally fits into the PDCA cycle (Plan–Do–Check–Act).

Kaizen supports rapid organizational learning. Why? Because small changes mean low costs of mistakes. Big mistakes are expensive; small ones carry little risk. Simple in theory, difficult in practice. What is big and spectacular is always more tempting. There is an unwritten rule: “fail fast – learn quickly and cheaply.” A mistake is not a failure – it is information about the process.

Marginal gains are small, individual improvements that are unimpressive on their own. Examples include:

Each of these changes seems insignificant on its own.

On a daily or weekly scale, they are often barely noticeable. Their value becomes visible only in the long term – months, a year, or even years. That is why many organizations ignore them. They lack patience and trust in small changes. Yet these changes form the foundation of Kaizen culture. For an operational employee, even a small improvement that is implemented and noticed by management is extremely important – it strengthens the sense of agency and real impact on the process.

Saving one minute per day may seem minor, but over a year it equals six hours. Improving by 12.5 minutes per day means 9.5 working days per year.

And what happens when such small improvements:

This is where the concept of the aggregation of marginal gains comes into play.

The aggregation of marginal gains means summing small improvements across different areas of a process.

Look at this.

We blindly assume that 1% + 1% + 1% = 3%. Is that really true?

What if 1% + 1% + 1% could give us as much as 27%?

How is that possible? Let’s look at an example. Consider three common business variables:

Let each of them change by just 1%.

Here is an example of a company that had EUR 3 million in revenue in one year. In the following year, it improved results in these three areas: annual revenue increased by 1%, margin increased by 1%, and fixed costs were reduced by 1%.

What happened? Profit did not increase by 3%, but by 27%.

Just a few small changes – yet the cumulative effect is already spectacular.

In a production environment, this can mean:

Maintaining changes over time is crucial. A single improvement does not justify a revolution. Their sum, however, begins to affect production stability, costs, delivery performance, and efficiency indicators (OEE).

We often hear that Kaizen not only fails to deliver results, but also creates more chaos than value.

Yes – but only when Kaizen is introduced without a system and without a cultural change.

Smart Kaizen works.

The most common problem is not a lack of ideas or employee engagement. In healthy organizations with high psychological safety, people want to improve their work and generate huge numbers of ideas. The difficulty appears when Kaizen is reduced to a set of initiatives without a cultural foundation. If an organization implements only the most financially attractive ideas, it quickly loses team engagement.

Another issue is the lack of an effective system for implementing ideas, consistency, and visibility of results.

In many companies, Kaizen often ends with:

Without permission to experiment, make mistakes, and learn, Kaizen turns into a short-lived initiative that frustrates employees instead of supporting them.

Without data, it is hard to prove that small changes work. Without metrics, they are hard to maintain and notice. Without tools, they are hard to scale.

The aggregation of marginal gains requires data. Without it, assessing whether a change actually works is difficult. Data allows comparison of the “before” and “after” states and supports fact-based decisions rather than intuition.

However, data alone will not build Kaizen. Without a culture of trust and continuous improvement, data remains just numbers in a report. Only the combination of Kaizen culture and data enables consistent PDCA cycles and faster organizational learning.

Effective Kaizen requires answers to very specific questions:

Without data, Kaizen is based on intuition. With data – it becomes a management tool.

In practice, this means:

In modern production plants, the aggregation of marginal gains is increasingly digital rather than paper-based. IT systems support:

This is where Kaizen stops being just a philosophy and becomes an operational, data-driven system.

The aggregation of marginal gains – and Kaizen as a whole – will not work in an organization that does not allow mistakes or expects immediate, spectacular results. This approach requires:

Kaizen culture is not about blaming, but about trusting operational employees. It assumes that even small changes matter – both from a business and a human perspective. This culture enables true aggregation of marginal gains.

In projects delivered by explitia, Kaizen is increasingly combined with:

Thanks to this, the aggregation of marginal gains becomes tangible – expressed in numbers. This allows companies to see real effects: shorter downtimes, more stable production, and better predictability.

Most often, the problem is a lack of data and information. Teams implementing marginal gains aggregation and other Kaizen tools usually struggle with:

Kaizen without the aggregation of marginal gains quickly loses its meaning. Individual improvements do not build an advantage. Advantage comes from a culture of continuous improvement and the aggregation of many small changes.

The Kaizen method is not about big slogans or breakthrough projects. Its real value appears when an organization systematically collects, measures, and sums small improvements.

The aggregation of marginal gains is the result of culture, reliance on real data, and consistency – in that order.