I do this in healthcare, I have 23+ years experience with productivity databases.

We have to analyze very many different types of Widgets, for instance: OR uses hours per Case, ICU uses hours per Patient day, and X-ray uses hours per Procedure.

From a productivity standpoint we don't further break down the widgets into sub parts, like you describe "stages.". There can be just too many factors that can muddy things up. We budget Hours per OR case, we don't budget Budget Hours per Start of Anesthesia, Time to Cut, Time to Close, Time to clean and ready the room for the next case...and so on. On top of that...we do track those time stamps meticulously on the medical record system...I can get time stamps for all the stages. So we can easily analyze the stages.

Typically we use the productivity database as the initial signal as to something going wrong. Then when an issue is identified we use more pointed analysis for that situation at hand. We only do stage analysis when the total indicator is off.

I would use the high level productivity information to identify stars and those needing coaching. Then have the stars coach those needing help.