I would have thought a submarine could sometimes hit a crisis that required all hands. But a stronger example might be drone pilots.

Possible, but that's when you pop your caffeine gum (or your speed) and skip a nap. I know that submarines are space-limited, and so dropping the crew requirements might be helpful- I'm not sure what the limitations are for drone pilots. (The flexibility that means they don't have crises might also mean there's no real gain from having pilots that can be awake for more of the day.)