going prone to save yourself is a misconception, probably spawned from the shallower or smaller drops that don't actually hurt you much if at all whether you stand or prone. on those hills it is important to move backwards to slow yourself down but standing our crouching just results in you walking backwards up the hill, crawling is slow enough so that it doesn't completely counteract the fall.
the only way to actually survive a cliff or steep drop is to jump backwards at a steady interval.









<--