The kid's preparing for a 4 MIiler is Sept. He's built up to a 30min. Tempo at 7:14min/mile; obviously holding back a little, since he's done 2min. increments over the weeks; His typical 20min Tempo is like 6:40 pace. He's doing his 5K time trial July 2nd., so he has 2 more tempos and one more interval session before then. He runs 30-40miles/wk, cross trains with cycling, swimming, and calisthenics (core, single leg squats, push-ups, swiss ball work, balancing exercises, lunges + twist w/ 10lbs. plate).
Also, when would you say it's time to start doing half-mile, mile, and mile-and-a-half repeats? Thanks for reading!