Like many here I've found normal use with mid to low quality scopes and mounts, even if properly mounted, result in more POI shifts than quality gear being bumped.
I can think of no instances that I have slipped and fell, knocking a good scope and ring system so hard that it wasn't zeroed any longer. I've had horses loose their footing and roll with a rifle in the scabbard, which held zero. I've put some noticeable dents and scuffs in the ocular bell of scopes when I slipped and fell on some rocks, which also held zero. Maybe I have just been lucky but you gotta knock them pretty damn hard if you got good equipment and they're mounted properly.
