Worktrees share more git state (remotes, blobs, etc.) and don't require hunting down the repository url to feed to git clone, or a network connection to use said url. While you could get the same benefit from cloning your local repository, you're then in the weird state where `origin` is a local non-bare repository.

If you're setting up long-lived checkouts that you reuse, it doesn't help much (except perhaps saving space or bandwidth) vs multiple clones and some once up-front reconfiguration. On the other hand, if you want something more temporary - and perhaps based on your current HEAD without having to hunt down a commit id to feed a subsequent git clone / git checkout command - worktrees save you some boilerplate (re)configuration.

It makes coordination easier. For eg if you want to fetch and pull master, you only have to do that once. If you want to rebase checkout A's branch on top of B's, you can just do that, you don't have to push between the two.

Less space.