I've occasionally speculated (which is all it would ever be--I'm permanently injured) about doing 20 quarters every day for a year (or however long). Including race days? Not including race days? One day "off" each week (for a long run, or race, or whatever)? Who knows?
This was inspired by the story of the guy who set my high school's mile record (which is *still* the record, 40+ years later). Every day (of practice), he would run 20 quarters; then he would do the team practice (typically not a lot of volume and only moderate intensity, BITD).
Thing is, there are so many ways to "run 20 quarters." I mean, I suppose you could run them at 2:00 pace with zero rest between reps; or run them at whatever pace, with a half-mile run after each (= 15-miler); or do them in sets; or do a classic Bob Timmons "on 3:00" workout, with cal or weightlifting between reps; et cetera.
I think I'd want to have several convenient venues that I *knew* were 400m (or probably an actual 440y, given my old-fartness). I just think it could be kinda fun, or at least a real learning experience.