I just want to say that taking a break every 4 weeks or so has been very beneficial. If I don't make an effort to take a break, my body will (without warning me). Twice already my body has let me know that it doesn't want to increase 10% the next ride after about 4 weeks of increasing mileage. When I don't take a break, I end up having a crappy long ride. So...for anyone else training for a century, take a break or just don't increase once in a while. After taking a break, I find that I ride a lot better on my next long ride!

When I say "break" I don't necessarily mean taking a whole week off, but maybe decreasing intensity on rides that week and doing a shorter ride on my "long" day.