I use celery when I need to launch thousands of similar jobs in a batch across any number of available machines, each running multiple processes with multiple threads.

I also use celery when I have a process a user kicked off by clicking a button and they're watching the progress bar in the gui. One process might have 50 tasks, or one really long task.

Edit: I looked into it a bit more, and it seems we can launch multiple worker nodes, which doesn't seem as bad as what I originally thought