During the pre-flight and when pushing or pulling a plane back into the hangar
Once again, as we dinosaurs know well, this is fine just so long as you know that turning a prop through a compression can cause a hot engine to fire with the mags switched off.
I shudder when I see students assiduously doing their pre-flight and grabbing the prop to give it a turn on an aircraft that was landed and vacated 15 minutes before by the previous user, and I look away when I see people grabbing a hot prop to move an aircraft that landed 5 minutes before. Trust me; it happens.
It's Darwin Award territory.