Fact: High speeds require fast contracting fibers
Fact: Endurance Requires a high aerobic capacity
Fact: High level endurance training elicits intermediate fibers
Fact: Low intensity aerobic exercise, regardless of duration, does not call upon glycolytic fibers.
Low intensity running for long durations increases mitochondria
Hypothetical: Give a Young Running this training theory, and literally have them run with it.
Once a week: Brutally intensive Lactic work, possibly twice a day; medium rep number, low recovery compound lifts (lunge, deadlift, squat, leg press) and/or circuit plyos
Twice a week: High speed, Alactic sprints 20-100m, full recoveries; low repetition, high intensity compound lifts, plyos and explosive lifts like power cleans, jump squats, weighted broad jumps, etc.
3-4 times a week: Very low intensity running; as slow as necessary to recover from workouts; practice running as mechanically "perfect" and efficient as possible; run as fast as you like on days you are feeling well, just so long as you do not feel the slightest burning in legs or shortness of breath; let's say anywhere from 6:30-10:00 pace for extended periods of time (2,3,4? hours daily, maybe broken up throughout day)
Is there any reason this would not produce a quality result at any distance 400m or greater?