Also remember that there were runners in (roughly) this time frame who had a very structured week. DeCastella was at 2:14 in 1979 and 10th in Moscow and 2:08:18 in 1981 (so about 5 years behind Rodgers in terms of being at the same level) and he ran 135-140 miles a week YEAR-round on the same schedule ... the same daily schedule.
Now, he raced less (for a lot of reasons -- being in Australia isolates you -- and by 1981 the money was better and he was a big deal by then) but his training was VERY rigid and the same every week.
My point is that if you could handle running 130 mpw, some people could not really excel under an approach like Rodgers, some people would flounder under an approach like Clohessy had DeCastella doing, and some people might not tolerate a plan like Shorter's. But they were 2:08, 2:09 and 2:10 marathoners from close to the same era. Same thing with Derek Clayton, his approach would not work for most people.
I have to comment that I doubt Rodgers was running 8:00-pace as someone said. I doubt he ever ran that slow. Maybe Bob Hodge could comment, as he knows best, but BR ran nearly ALL his marathons at 4:56-5:05 pace (2:09-2:13). If he was tired enough that he needed to run 10 miles at 8:00-pace I think he should have been resting.
My hunch is that "OK" pace actually meant faster than we would guess. He was consistently in 28:30/2:10 shape on the roads and had a couple of 28:05s on the track. Compared to the 34:00/2:36 road racer, that is 1:00 per mile faster in races.