I agree that high mileage is "outdated" (in general) for 800 athletes, I'm positive it's still the best route for some, but probably not most. On the flip side, super duper low mileage is also the best route for some, but definitely not everyone. I feel like most elites are in the 30–70mpw camp. That's a broad range, but at the very least, the 30mpw guys do some form of easy, slow running.
You mention Jones, and I've been curious about UT & Texas A&M's training for a bit. I know Texas A&M used to post workouts on YouTube and it was fun to see. They'd do stuff like 1000/800/600/400/200/200. But as far as I know they never really went too in detail about what a full training week was or how they periodized. I can only assume that they do some form of easy mileage, even if it's 1–2 on the warmup and another 1–2 on the cooldown some days, that could easily turn into 20 miles of easy aerobic running.
Alan posted Juanterna's training. In the first section he just says "warm up" and "cool down". Later in the document he says things like "3k cross" for a warmup, which I can only assume means 3,000m of off road running. Which again, can easily add up to 20 miles of just easy running. Even Clyde Hart had his 400m athletes run 1-2 miles now and then.
If we're talking real 400/800 guys, I don't think 20 minutes worth of tempoing or fartlek is a requirement at all. I don't think running a long run of 6-7 miles is a requirement, especially at the high school level. I think true speed based guys can replace those types of sessions with things like, idk just making this up, 20x100 @ 17s w/ short rest. But that's a far cry from the mentioned 5x1000 @ 2:42. The 20x100 will be a brisk walk in the park, a little burn, that 5x1000 will make you see god.
Not sure where I was going with this, but I think it could be a dicey to plan ZERO easy to moderate aerobic efforts for almost (I said almost) all 800 athletes.
Someone tell me why I'm wrong.