You just don't want to over train and burn out. If you have the luxury and don't feel like riding one week. Don't. It should be fun 
If you are riding on a trail instead of the street, you may want to do time instead of mileage as you get farther along. The Katy Trail in Missouri is fine gravel and slows me about 2 mph, compared to the road. If this is the case, you may want to consider seat time instead of mileage, or a mix of both.
"Well-behaved women seldom make history." --Laurel Thatcher Ulrich
'09 Trek WSD 2.1 with a Brooks B-68 saddle
'11 Trek WSD Madone 5.2 with Brooks B-17