yeah, i know almost nothing about jj because i only use it via jjui. Why would I waste brain power learning about and remembering new incantations when I can just browse around with arrow keys and mouse and then use like 9 hotkeys to do everything that I could possibly need?

I use jj fairly regularly and I'm trying to understand what your approach means, but having difficulty following what you want to acheive here. Seems like you're using ambiguous language that isn't aligned - wdym by marks?

In jjui, you can select multiple changes to squash/rebase by pressing space bar before pressing S or r. Is that what you mean?