Just because someone writes a book on dog training or professes to be a dog expert doesn’t mean they are one or that the book is reliable. One example is Dog Obedience Training by Milo Pearsall. He advocated praise, but after a negative punishment for misbehavior. This probably sends a lot of mixed messages to the dog. That is the big problem, mixed messages. Just because we think we understand a method, doesn’t mean the dog does. We don’t know how dogs think. One thing is sure, no animal wants to be hurt, and if they are the hurt stays with them. There is no telling how that hurt changes the animals attitude toward you the handler. I maintain the best practice is, don’t ever hurt the dog in the first place and don’t allow anyone else to do it either.