A few more things to add to this discussion (really interesting conversation, by the way).
1. I agree with Doodoo - I think it's normal (and relatively vital) to take some period of recuperation during very high volume training. For me, that doesn't usually mean taking a week where I run 75% each day, but instead, I would take 3 days where I run VERY little (30-60 minutes only) every 20-25 days. I found that this super-recovery gave me a huge mental and physical break and allowed me to recover and then get back into a big block of training.
2. It sounds like this poster followed a similar trajectory to my own. I ran ~27' off of 80-90 MPW and then ended up running 30'22 for 10k in college off of 120+. Still, I think that this can be a bit of a misinterpretation of the results. While the increase in mileage surely had a big impact, I think the bigger impact is the fact that a couple of years of consistent training passed between those times.
What I'm trying to say is that you can't expect to go from running 27' for 8k to 25' for 8k in a month just by increasing your volume by 50%. Yes, my volume increased by 50% and yes my time went from 27' to 25', but that happened of the course of 2-3 YEARS! The thing about mileage is that it's a long, slow, patient game and if you want immediate results, you might be disappointed.
Finally, to comment on a poster who mentioned the idea of talent and durability. I think he's right and there's a huge misconception that TALENT can only be measured in how fast you can run 400m or what your 5k time is in high school. Surely, this natural ability is extremely valuable and a great indicator of future success. But, the idea of being durable and being able to train at an extremely high level without getting injured is a huge outlier and therefore I would call it another form of talent.
I'm the perfect example of someone without very much of the first type of talent (slow of 400m, slow in HS), but enough of the second type of talent to let me see some serious improvements.
So, yes. Having success with very high mileage is not JUST about work ethic. You can "want it" as much as possible and go out and put the runs in, but your body needs to be able to accept it. Call it talent, call it durability, but it's something that not everyone has, so count yourself lucky if you can handle it.