I generally use autosquash when a code review of a PR turns up things I missed, which should have been part of a particular commit on that PR's branch. However, I don't want to amend the previous commit right away if I'd like another review for the new changes. Thus, I do a `git commit --fixup <HEAD|hash>` and push it. I can then ask the review to only look at the new commit, I won't break their local checkouts of the branch, and only when everything's been approved I run `git rebase --autosquash` and then merge it in.

(Before I started using autosquash for this, I'd do the same, except I had to figure out at the time of merging onto which commit every new commit had to be fixed up, rather than at the time of writing it.)