Planting with post hole digger/auger
I see people doing this to plant large numbers of trees quickly.
It sure beats manual digging if you have a few dozen trees to plant, but you can't really make the "bowl shaped" hole this way, it's more of a straight sided hole and potentially could go too deep if you can't wield the auger correctly and back off at the right time.
There could also be "glazing" on the hole sides depending on soil type.
Has anyone done this and could you give pointers on making it work?