I was once on an LGA-ATL Thursday night 757. High-fare FO at the time, and I think I was still in the 130s or 140s after BFUGs had cleared. There were a dozen or so people behind me.
The scrum that happened during SP boarding was quite a sight. With just my briefcase in hand, I waited until Zone 2 and leisurely boarded with the 2 other people left in the gatehouse.