It used to be the worst checkpoint time at IAD was around 7:00 am, but that's been an easy time to clear security of late IME.
One problem I've seen is that there is little enforcement of the premium lane. I've seen pax arguing amongst themselves as they approach the checkpoint: "Now, Bill, that line is for premium passengers only!" (they both have big UA "ZONE 4"s on their BPs. Bill says to his companion: "Hey, *I* say
you're premium, honey!" No check or sending them to the other line by the BP / ID checker, either!
