As well as everything said so far, my reasons for turning a prop by hand in past years have been:
- to clear the nosewheel tow bar (on the club Fuji, which has long prop / short nose leg) - the prop pretty well always stops in the vertical and requires turning horizontal (having checked I've got the keys in my pocket!)
- the PA28 which I had a share in at Bournemouth was parked outside. It also had a very small / slightly k*ackered battery. In cold weather, my standard procedure was to prime the engine, pull it through 4 blades, one more squirt of primer and then attempt to start. This worked most times and saved having to prop swing a live engine, which I try to avoid if possible.