Read Joe Friel on cycling training. CbadRider is quite right. If you want to increase your speed, you need to train with intensity. But you can't do that all the time, you need time to recover and distance builds strength and aerobic capacity. So your training should consist of a mixture of LSD (long steady distance) rides, with occasional interval sessions of a severity that make you want to throw up. Once or twice a week is enough for those.