This is something I've been wondering about for a while. I generally put in fairly high mileage, but I get really burned out mentally after a few weeks in the 85-100 range. Also, if I'm honest, I really don't have a good reason to train at that level any more, other than I'm just used to it. I mean, I'm out of school, and I'm not making any income from racing, but I do still enjoy being able to run a fast race.
Anyway, my question is, what pros and cons might be associated with shifting from, say, 100 miles in 7 days (~14-15 miles/day on average) to something like 70-75 miles over 5 days (still 14-15 mi/day), with 2 days off? What added benefit am I gaining by putting in another couple of easy days as opposed to having a couple of days off? I understand that there will be some aerobic benefits from running those extra miles. But it seems like two days off would allow for training at a higher intensity on daily runs, with longer and/or higher-intensity quality sessions. Which would provide a greater benefit?