Aside from lost luggage, I can't quite get my mind around why, at certain hubs (looking at you, PHL), I have never waited less than 30 minutes for bags to arrive on the belt. It is often longer, and often with multiple changes of carousel and with the flight disappearing from the arrival/carousel display screen altogether.
At other hubs, priority bags often come out last. There are some places, like LGA, where IME bags are handled efficiently, and where they actually set Priority bags aside. But the inconsistency of the baggage handling across the operation is absolutely maddening.