I've found that the cabins in the aircraft and routes I've been flying have been almost at capacity this summer, even on routes which I have noticed are often not too full, at least at the times I fly. My most frequent routing is CVG-ORD-YYZ, with the ORD-YYZ usually having a good amount of capacity left. Even at some of the more peak times, I think I got an upgrade every flight on these routes between UDU starting through June.

In July and August that hasn't been the case, even at non-peak times. Obviously, would rather have the upgrade, but I'm not complaining. My CVG-ORD on Wed. evening had every seat full. My upgrade on the YYZ segment cleared a few hours prior to the flight, and I think there were 4 seats empty on the entire plane.

See this as peak travel filling the seats. It sucks to have to sit in E-, especially on longer segments. But am happy that UA is filling more seats.