When companies begin to implement the four lean principles just mentioned, they often come to an understanding. It becomes clear to those involved 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 closer and closer to the actual needs of the customer. This is the fifth and last Lean principle: continuous and never-ending improvement, or Japanese Kaizen.
Each of the first four Lean principles is interlinked. If you want value to flow faster, you still have to discover a lot of levers to turn to perfect production. This means that the more the customer demands (pull principle) the faster and more evenly the desired added value must flow through production. The elimination of Muda naturally requires new process technologies and new product concepts. 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 see the overall process in order to provide suggestions for improvement. The participants thus receive immediate and positive feedback on any improvements made. This usually serves as an incentive for further improvements.
One method to support Kaizen is the Plan-Do-Check-Act cycle (PDCA). With this evaluation process one can check proposed improvements and adapt them if necessary.
In summary one can say that the constant striving for perfection in this context also includes the constant questioning of the preceding 4 Lean principles. Thus a continuous cycle of all principles is formed. This results in a continuous improvement process, in short CIP.