This is pretty much the way I looked at it too.
Advancement at UPS is more about good judgment than being intelligent or book-smart.
A good management person learns to make the "optimal" decision not the "right" decision.
It's about making a decision or taking an order and doggedly pursuing it to completion.
That means not letting any emerging "facts" deter you from your goal.
My observation differs some. I don't know about other than operations, but most(not all) sups looked(look) frightened and could be fired at any second. And would do anything(literally) to make those numbers. Managers, not so much but watch your back and have seen some make horrifically poor decisions along the way with poor judgement. Most Div. mgrs are really type AAA and are wound way too tight. There are exceptions but not alot.
I have also thought that I would last about a day in mgt. before I spoke my mind about a policy or decision or some such and like has been said, and be fast tracked for termination. I am not shy nor complacement. Example: I was nearly hit by a falling package(50 lbs.) from 20ft. above on the belts. I conveyed my unhappiness to the div. mgr, ft sup, pt time sup....quite loudly and with passion.
In the end, staying hourly probably allowed me to complete 32 years.