I've coached at both the high school and collegiate level....currently back in the high school ranks. I've personally had the following athletes in HS over the past years:
Men:
400 47.3
800 1:52.2
1600 4:11
Women:
200 24.4
400 54.5
And some nationally ranked relays as well....
I don't know if you'd consider any of those "once in a lifetime." But, you would be crazy to think that we didn't alter workouts for those athletes. A couple reasons come to mind initially....
1. College coaches want kids in their programs who can handle college level workouts. Raw talent is great, but if they can't handle workload or mileage, they are ultimately useless and won't progress at the next level.
2. I write all of my workouts based on the "best" athlete I have and then volume/intensity trickle down based on talent. If we've got a girl running 55 seconds in the quarter mile....a workout might be 6 x 400 in 63 with 2 minutes recovery. The other girls will do 65-70 with 2:30 or 3 recovery....and we will pull them from the workout when it appears they're toasted. No reason to fry the nueromuscular system, unless the next day will be completely off....etc.
3. Every kid is treated fairly....NOT NECESSARILY EQUALLY. This is an important point in our program....the girl who runs 55 seconds is going to get more attention, have more leaniency with tardiness/problems/etc, more flexibility with choosing her events/workouts. This goes without saying, and is a no-brainer to me. Many other coaches I've talked with disagree vehemently.