Limiting WIP reduces lead time by reducing multi-tasking.The term “work in progress” describes all the things you have started working on and are continuing to do so.A WIP limit is the maximum number of tasks that you allow to work on simultaneously at any given time.
When there is no WIP limit, we tend to start with more then one items in given time, which leads to distractions, less focus and biggest waste in my view associated is context switching. And this eventually leads to poor quality and dissatisfied client.
Since we are talking about WIP limit, how do we identify personal or team's WIP limit? How do I reach to number n?
Start simple, match your work in process to your current capacity.Ideally we would like our team members to work on one item at a time, but we should look to enable some slack to allow for blockers and expedited items. For a team of 6 perhaps a total WIP limit of 9 should be initially set. It doesn’t need to be exact, adjust as you go. Revisit the limits, either increase or reduce by 1/2 if bottlenecks regularly appear. (PDCA)
Having high WIP limits means that probably your team is working on multiple tasks, switching context all the time and not meeting the deadlines. Having really low limits on the other side means that when a given item is pending on third party, and team members are idle.
What these two scenarios have in common is that your team is unproductive and inefficient. In order to have highly efficient teams carefully inspect your KPIs when you either increase or decrease your limits. If you change your team’s WIP limits and your KPIs go in the opposite direction of what you’d expect, then you’re probably doing something wrong and you have to re-inspect closer to ensure smoother flow.
Without WIP limits, progress on process improvement is much slower. Teams that have followed this from the beginning have reported superior business results with reduced lead times