Those are the 2 mile times run during the xc season for the national postal meets. The track records are of course overall faster and deeper as it's later in the school year and there are more opportunities to run the distance. But they are also a mid October gauge to see fitness level before the conference, regional, state meets.
The thing with the summer program was 1000 miles considered an optimum number to build a base for the fall. There was an occasional track workout but it was optional as was everything else, although Mr Newton would growl sometimes at a top guy if he didn't see him for a few weeks with something like "Where the hell have you been?"
Some guys ran well over 1000, some didn't; some ran the occasional track workout, some didn't. But those were not every week and they were the only planned workouts that Mr Newton actually conducted. He gave us a guideline of workouts to run on our own, but it was up to us to do them and in the end of you followed the guideline you would hit 1000.
I personally only did a 20 x 400 once each summer just to break up the slower, longer mileage. I also would run a few summer xc meets where I could gauge myself against guys from other schools who would show up and as a confidence builder. Overall I'd say most of us 1000 mile clubbers ran just over 1000, a few guys would run more but that didn't necessarily mean they improved more than those who ran less.
I think I remember your sons, they were good and I believe had good college results too, but I myself could never do 120 mile weeks or 20 mile days. I never liked to do more than 7 or 8 mile runs. I would do those in the morning, then work, then an easy 3 or 4 mile run in the evening, unless I was going to run a summer meet or decided to do a track workout. Most evenings where I knew guys would be meeting up at the school I'd run out to the school hang out with the guys and kind of "check in" with the coach.
My progression in high school?
Freshman 11:08 (no summer mileage)
Soph 10:37 (550 miles)
Junior 10:09 (1070 miles) One Camp Olympia week in August where we hit 100
Senior 9:46 (1130 miles) Another Camp Olympia week for 100