I'm speaking from my daily experience. Sometimes i don't want to close my laptop before going to bed because there are still 1-2 tasks ongoing in my AI kanban board, so I just leave my laptop open (lock but not suspend it) so that the agents keep working for a while. I don't even have things all that automated.
I anticipate that once I have some more complex agentic scaffolds set up to do things like automatically explore promising directions for the project, then leaving the AI system on overnight becomes a necessity.