John Kellog and the brojos preach high mileage, and that athletes should eventually be running as much as 150 miles per week, much of it at an easy pace (7:30 miles if that is what feels "easy"). In the training podcast, rojo says that there is no need to run steady or moderate on a non-workout day because it is still not at threshold pace, so you're not getting that physiological benefit, and you're also exerting more effort than you would at an easy pace, so you're tiring yourself out more for not much of an increased stimulus (as they say).
Peter Coe says in his book that athletes should limit their volume to the very least needed to achieve their goal. He also says that the quality of what you do is much more important than the quantity of what you do, arguing it is pointless to run (relatively) slow miles when you can develop an athlete with quality. Seb did no more than 70 miles per week (according to marius who has copies of seb's logs and spoke to peter and seb about this subject specifically), with much of his over-distance runs on the road at 5:20 mile pace or faster (much of it faster - 10 milers in under 50'...etc).
I don't want this to be a debate about how many miles Seb really ran, or if doing race pace repitions year round is beneficial, but rather a discussion on a high volume of easy miles with 3 or so workouts per week, as john kellog and the brojos advocate vs focusing on a lower volume of steady state pace running with a lot of runs finishing at LT pace.