When companies begin to implement the four lean principles just mentioned, insight often comes. Those involved realize that processes can always be further optimized and improved. The companies realize that effort, time, costs and errors can be reduced more and more. At the same time, they can offer a product that comes ever closer to the customer's actual needs. This is the fifth and final Lean principle: continuous and never-ending improvement, or Kaizen in Japanese.
Each of the first four Lean principles is interrelated. If the value is to flow faster, you still have to discover a lot of adjusting screws you can turn to perfect production. This means that the more the customer demands (pull principle) the faster and more consistently the desired value must flow through production. The elimination of Muda naturally requires new process technologies and new product concepts in some cases. Nevertheless, the technologies and concepts are usually surprisingly simple and ready for implementation.
One of the most important aspects of continuous improvement is transparency. Everyone involved in the production process must be able to view the overall process in order to provide suggestions for improvement. In this way, those involved receive immediate and positive feedback on an improvement that has been made. In most cases, this serves as an incentive for further improvements.
One method that can be used to support Kaizen is the Plan-Do-Check-Act (PDCA) cycle. With this evaluation process, one can check proposed improvements and adjust them if necessary.
In summary, it can be said that the constant striving for perfection in this context also includes the constant questioning of the previous 4 lean principles. Thus, a continuous cycle of all principles is formed. This results in a continuous improvement process, or CIP for short.