concept WIP limit in category kanban
This is an excerpt from Manning's book Kanban in Action.
The WIP limit isn’t a strict rule; it’s a trigger for discussions.
From the previous chapter, we hope we have now convinced you that a lot of good things come from limiting your work in process (WIP). By now you’re probably full of questions: What is the right limit for you? How do you go about finding the WIP limit? Are there some good starting points that can guide you?
As you soon will find, there are no hard rules here. Finding a suitable WIP limit is not only contextual and dependent on what you want to achieve, but also like hitting a moving target. The WIP limits can and should change. At the outset of this chapter, we can already reveal a secret: the goal is not to limit WIP. WIP limits are only a means to drive you to improve. Improve to achieve a better flow, which is the theme of the next chapter.
In the figure at right, you can see a WIP limit of 4 for the Development column. The column is then split into two sections: Doing and Done. The developers are working on one item and have three items completed, which keeps them at their WIP limit.
Another way of visualizing this queue could be to have a Ready to Test queue column in the Test column instead. That would then count against the WIP limit of the testing step.