I have been finding the workflow I described to be quite helpful, because it also provides me a scratchpad that I associate to the branch. And since the tip is never the git head so when I have to fallback to git I'm "sure" I'm not operating on that.

I'm still experimenting with things, but I think my overall takeaway is that in jj my working copy is "on branch", so I should lean into that rather than try to emulate my older workflows too much. And this new workflow... I just find it better!