Just responding to Coe fan, how fast you run as a youth does not show how talented you are. It just shows that you are more mature or harder trained at a young age in most cases. Also, Seb ran 46.90 and 46.85 open 400s at the same meet (trials and finals). Ovett when he was 15 and 16, in his book stated that he trained harder than neccessary according to Frank Horwill. At 16, Horwill told him that because he was doing other activities all he needed was a 4 mile run most days while Ovett said he would go for 10 miles.
Also, usually with mileage debates, the low mileage runners are exaggerated as well as the high mileage runners. Coe, in his book, states that he DID do 14-15 mile runs and even as a 13-15 year old would run 10 miles at 6 minute pace up hill EVERY WEEK. Coe never states his mileage in terms as highest, only in avgs, one particular winter he avg 75 miles a week, for a 46 seconds quarter miler.
So Coe, who included intervals all year around to boost endurance (Training Distance Runners sites long interval workouts) did less mileage but it evened out toward peak period where Ovett's dropped considerably and Coe's dropped, but less.
Assume that for each second lost over 400, you must train 10-12 miles more a week and you have your typical 48 quarter miler (Steve Scott) running upwards of 95-100 miles a week during base period.
Coe's program is actually more like today's current training according to Marius Bakken who is currently on the circuit and gets his insight from other runners. He states that avg milers run upwards of 100 miles with tempos and long interval workouts (summer of malmo) during base. Assuming most are 47-48 400m runners, this is in-line with Coe's training.
It should be noted that Ovett never neglected being fit at any point and it evidence by 6-8 x 1000m and 10 miles in 52 minutes weekly (tempo and long interval workout). As evidenced by the training posted, 20-25 miles of shake out is included in that 100+ total, assuming this did not significantly aid Ovett's endurance, it could be neglected in lieu of additional sharpening, such as a light speed session.
And finally, Ovett was 155 lbs. versus Coe at 130. It is usually true (from my evidence) that more weight INCREASES the need for somewhat elevated mileage. Example, 100 lb Laban Rotich could run lower mileage than Paul McMullen being that his light weight is already EASIER to carry and more efficient over a mile distance.