When I develop roll films, I generally use 3 inversions every minute or so - unless i have a good reason for doing something else. 35mm film I give 2 inversions every 30sec - it's all just habit.
Sheet film in tank gets 2 inversions every 5 minutes with very dilute developer - almost stand development. Or it goes in the tray, which could be anything from continuous to 30minute intervals depending on flim, developer and subject.
So I won't vote :P