Pedex,

I partly agree. But I would disagree that a person has to do 3-5000 to see improvement. Even if a person only did 10miles a week they would see improvement. No, not to race in a local crit but to improve from a sedentary life style.
When I started riding with my wife we did 10, then 15 and kept increasing the number of miles per ride. She did her first century with an average speed of 16mph in less than 2 years. Not phenomenal but an achievement nonetheless....considering it was a hilly century and that was basically solo without a draft.

Not everyone can build base miles of 60 or 100 per week. It all depends on the personal goals each person has that should drive the intensity and style of training. But I certainly agree it takes time and that's why it should be fun.