This restriction of git worktrees is annoying but I just learned one simple rule to follow:
Never check out the main development branch (main/master/develop/etc) in other worktrees (non "main worktree", using git-worktree nomenclature)). Use other name with "wt-" prefix for it. Like in:
And to be honest, after being disciplined to always do that, I very rarely get error message saying that the branch I want to check out is already checked out in other worktree. Before that, I regularly had a situation when I checked out main branch on second worktree to see the current state of the repo (because my main worktree had a work in progress stuff) and after some time when I finished work on main branch, I tried to check out main branch on my main worktree and got the error. Because I totally forgot that I checked it out some time ago in the other worktree.
git worktree add ..\repo -b wt-main --track origin/main
And to be honest, after being disciplined to always do that, I very rarely get error message saying that the branch I want to check out is already checked out in other worktree. Before that, I regularly had a situation when I checked out main branch on second worktree to see the current state of the repo (because my main worktree had a work in progress stuff) and after some time when I finished work on main branch, I tried to check out main branch on my main worktree and got the error. Because I totally forgot that I checked it out some time ago in the other worktree.