Combining more than one stage under a single WIP limit
This seems like this should be possible but I can't find any guidance on how to best implement this. Can anyone point to some online resources or advice?
What do you mean by a "stage", and can you explain how one would be subject to WIP limits at all?
If by "stage", you mean a column that represents part of the workflow, then yes, you can have a WIP limit that applies to multiple columns. You can also have a WIP limit for each column as well as for a set of columns.
We can take a concrete example, perhaps from software development. You may have workflow steps for "to do", "in development", "ready for code review", "in code review", "ready for test", "testing", "ready for deployment", and "deployed". The steps of "in development", "ready for code review", and "in code review" may be performed by developers, while an independent tester takes over from "ready for test" and through "testing". As such, you may want to limit the amount of work that the developers take on to prevent overwhelming the tester. You can apply a WIP limit to the three states of work that developers take on as well as each individual column in that state.
I would strongly suggest that columns that have a shared WIP limit are consecutive. This is normally done because there is some kind of hand-off between people with particular expertise or that requires some level of independence to get to a done state.
How you implement this depends on the tools you are using. It's pretty straightforward on a wall or whiteboard. Some electronic tools may or may not support this, you'd have to look at the documentation.
I've worked with teams that would apply a WIP limit to a workflow stage but break the actual stage into 2 columns (we called them activities) on the board. For example, their workflow stages would be the following and each in-progress stage would have it's own WIP.
To-do | In Development | Code Review | Production Setup | Deploy | Done.
But the actual columns on the board would be
To-Do | Design | Code | Ready for Code Review | Code Review Complete | Configuration | Database Pre-work | Deploy | Done
The stages and columns that are in same fonts map together. So the WIP limit of 4 for In Development would apply to the combined total of all items in the Design and Code columns.
This was done so that the team could start to understand where certain activities within a "phase" were causing blockages or slow downs in work. The columns on the board changed as needed to properly diagnose problems. While this isn't actually applying a single WIP limit to multiple stages, it does allow more granular insights into activites during a stage. Is that what you are trying to do?
Thanks all - I apologize for the confusion. By stage, I did mean "column that represents part of the workflow" and/or "workflow stage". Apparently, there is no way to edit a post after hitting submit.
I appreciate the advice. I literally could not find any articles or blog posts on this. Could be I am just not searching for the right phrase.
The idea that columns on the board subject to a collective WIP limit best be consecutive and breaking a column into activities is very helpful. Thanks Thomas and Daniel.
What motive would you have for combining WIP limits as you describe?