" typical training session should run 30-90 seconds. Resist the urge to push longer, even if you’re doing well; that’s a great time to stop, before any mistakes happen! When your dog really understands this behavior, you should be completing about 15 target repetitions per minute. "

― Laura VanArendonk Baugh , Fired Up, Frantic, and Freaked Out: Training Crazy Dogs from Over the Top to Under Control