I've seen this at almost every high school I've been to. The distribution of 1600 times looks something like this:
4:3x
4:5x
4:5x
5:00
5:01
5:01
5:02
5:03
5:04
5:04
5:05
5:06
5:08
5:1x
5:1x
5:2x
5:4x
5:5x
6:xx
6:xx
7:xx
That's not everyone's PRs, but the pattern generally holds. One genetic freak running 4:30, 2 or so guys running 4:40 - 4:59, a ton of guys in the 5:00-5:05 range, and then a long tail of lazy and/or untalented folks running 5:20 - low 7.
That's a pretty extreme and sharp bell curve. Does anyone have any explanations for this?