Tips for Training Your Dog Various Commands
According to Dr. Nicholas Dodman, vary the commands during an individual training session – keep the training sessions short and frequent. Dogs will learn much more from regular, short sessions than from longer, less frequent ones. Once the dog has learned several useful commands on the continuous reward schedule, that is, the dog is rewarded for each successful performance of the behavior, the schedule should be changed to one of intermittent reward.
Dr. Dodman has some great tips in this article – please read 12 General Rules for Training Dogs.