Despite it not being the FT way, I wonder if there isn't more of this (especially at leisure times) than we might guess. I was on a flight recently (E75) that went out with empty seats in F, and yet there were several people in G1 sitting in Y (there were no uncleared upgrades). Non-CC elite awards was my only guess.

Interesting to see the upgrade ratio in F on the ORD 744. I was looking to SDC onto one recently, but it filled up 12/12 with paid tickets before T-24. I think the last two might have been a glitch since two upgrades had cleared by morning (and seats were never assigned), but still went out with 10 paid in F.