Looking at other people's code I vastly prefer a feature branch with a summary name of the feature "new-checkout-flow" or whatever and then the commits as they where without squashing/rebasing. Mine tend to have quite a few commits cycling through:

  - Stub in [classes/models/etc] for checkout flow
  - Add basic test coverage
  - Fix my API for easier testing
  - Decouple foo from bar in new flow
  - New checkout flow mostly tested
  - New flow UI cleanup and add comments
  - Fix nasty [N+1/O(n^2)/etc] performance bug in new flow
  - New flow feedback from acceptance testing
  - New flow ready to merge
  - [And often enough/honestly] "WIP to share with..." or just 
 "WIP" for work in progress, "Fixing bug in" or whatever reality there was.

Going back at `git blame` etc 5 years later i can see from the branch names linked to the commit the why it was added and from the commit messages I can see something of at what point in the mental processing of designing/implementing that exact line made it it.