Well, my opinion only: be careful following anything you read too closely.
That said, I think it depends on what you are doing. The system outlined in the book has you running "current" 5K - 15K pace during the base period, with the occassional mile goal pace reps for speed. During the season, Current pace gets closer to goal pace.
You do run lots of different paces. My concern would be that many runners, myself included, have trouble holding back. So if the workout is 4 x mile @ current 10K pace, I would be tempted to run a bit quicker. Do that a lot, and you find yourself a pile of dust before the first race of the season.
THE biggest mistake I made in college was running hard day-very hard day, for 4 years. It limited my mileage and caused me to be sick most of my senior year.
I like the idea of the Oregon system because I have trouble with the idea of spending 6 months doing LSD. However, be careful with the level of quality during the base period.
I could go on and on, but rather than hear it from someone that over-trained, or at least didn't train right, listen to some of the others.
Build your mileage while running 10K-15K pace once or twice a week. Toss in some hills or mile pace reps every couple of weeks, long runs up to 20-30% of total. Do that for a while and then your body will tell you when it is time to do more. I think the "secret" is to listen to your body instead of a book or some world class runner.