Hold it right that wrote:
Your argument is lacking evidence.
The overwhelming majority of programs base their training on mileage, not time.
Examples:
Coaches say: Run 8 miles. Not, Run for 60 minutes
Coaches say: We are doing mile repeats today. Not, We are doing 6 minute, 30 second repeats today.
Coaches say: Make your move around the 2-mile mark. Not, make your move around the 12:00 mark.
But, I would agree that by and large, girls train less (in mileage volume) than boys:
If a boy runs for an hour a day at 7/min pace, and a girl runs for an hour a day at 8/min pace, then the boy runs 17.5 extra miles. So I agree that in a situation where the race distances are equal. the girl runner is less prepared for the demands of the event, and should run longer in training.
Have you heard of Badger miles? They are pretty ubiquitous in successful collegiate XC programs. Successful HS programs too. Coaching speak in miles but plan by minutes.
They don't tell all 40 runners to run 8 miles. They tell the top group to go 8, the middle group to go 7, and the bottom group to go 6. And somehow they all finish within 5 minutes of a 60-minute run, why do you think that is? Because it's a 60-minute workout they have mapped out.
The mile repeats are 1/3 of the race distance (5k). Repeats are generally 1/3, 1/4, or 1/5 of the race distance. Also, mile is a convenient unit of measure and often everyone knows their goal pace in minutes/mile. Again, mile is used for convenience. If we were on the metric system, you'd see a lot more KM repeats (1/5 of a 5k)
The move at mile 2 because the race is 2/3 over and generally runners struggle from 2/3 - 3/4 so asking them to make a move gets them through the lousy part of most people's races. Having something to focus on during the rough patch improves the result. "Push the 3rd 200m" is common for 800m runners. Again, has less to do with distance but the percentage of the race.