Not a lawyer yet, but a law student who does some of the stuff you’re talking about, i.e. mostly knowledge management.
I do use Obsdn for notes/outlines/planning, but when it comes to long-form writing I use Docs or Scrivener instead.
I do keep “literature notes” in Obsidian - it doesn’t really make sense to me to keep this in a separate place, since you do want to link them across notes. But I guess it’s more of a personal preference; I try to keep everything in one place as much as possible.
I think I have a more structured flow than most users here. Inside the folder “LAW” I have a folder “[Court] case-law” and one file for each case - and structure notes on top of that. From there it depends on what I’m going to use the case for. Inside the case file I have links to concept notes, and also related case-law/legislation.
What I’m still struggling with right now is legislation. I come from a civil law tradition so I cite specific legislative articles more often than I need case-law, and I don’t know if I should have a note for each article - and if so, how to go about it, since there are way too many articles. But maybe I’m just being lazy about it.