I suggest to record all stages changes from a Business Process Flow on a "new entity" to store the actual start, actual end, duration, stage and Regarding to the main registry on the BPF Table.

It something that many Customers had asked me to customize and I'm sure It should be great to improve the OOB Solutions so we could use future improvements.

Till 2020 there exists some other fields (Stage ID, Process ID, Traversed Path) that now are deprecated without any other solution to replace it.