You can either have one “monitor” process for multiple workers, or have one companion process for each worker.
A downside of the former is that a single monitor might be a bottleneck if workers are frequently created/terminated. Moreover, a crash during the cleanup will crash all other pending cleanups (and maybe even all other workers).
A downside of the latter is process/memory overhead (for N workers, you’ll need 2N processes, or 3N if you introduce a parent supervisor for each worker-companion pair).
So, as usual, the answer is “it depends” 
