One of the big repos I interact with regularly is nix. It’s a massive monorepo for all nixos packages which is both good and bad.
The bad is that a full git clone dumps 6GB on my hard-drive that I don’t need, especially since I’m not working with the history in any way.
Some instructions on the nixos discourse pointed me towards a possible solution which is git worktrees.
I promptly deleted my local nixpkgs git repo and re-cloned it as a bare repo.
I don’t currently have any active PR’s to edit but will evaluate this approach when I do.
I don’t know that an analogue for this workflow exists in jj.