Since I started the thread, I better do some follow up here. The UAL flight to FRA I referred to is like Full with a capital letter. There are only about 2 empty seats showing and it's for a departure 2.5 weeks away.
I think this tactic works, that's why management keeps doing it. I am one of those anal people who want a sure thing so I book as far in advance as possible. Besides, I don't want to sit in the middle seat in a 747 for 9 hours squeezed between a 300 pound man on one side and a faintly foul-smelling lady on the other side. And a kid in the back kicking my seat the whole way. Just thinking about it is nauseating already.