As for the playing deaf thing in general, when you train, how many times will you allow yourself to repeat the command?
I do try to stick to one time only but I know I am guilty sometimes of repeating it once or twice.

When I had my first dogs years ago, I read the training manual How to be your Dog's Best Friend by the Monks of New Skeet. It has always been my favorite training manual because it uses natural methods that a dog can understand, using wolf pack behavior as a reference in teaching. The authors were very strong with the emphasis of giving a command once and once only. I think I will be more careful to make sure I am following that guideline.

As for the book, I still believe it is an excellent one, dealing with many different problem behaviors and dispelling a lot of old myths about dog training.