The problems in training retrievers but could apply to any type of dog training, it looks so easy, but, it is not ,it is very complex. Add the additional tools of classic e collar training with sound basics and many feel when the dog learns the trick of the exercise, without proofing the exercise they are through. They take it to the field before the dog is ready, it crumbles and create sometimes lifetime problems.Now we want to quick fix it.... Example Ff dog learns the trick, reaches for the bumper and wow that was easy. We don't proof the FF take it to the field and now we have mouth issues or bird issues and it goes on and on. Made a lot of mistakes before I learned through professional help about 25 years ago the classic basic training with the e collars. Trained a lot of dogs before that in so called positive training in many venues. It just didn't work for me. I was always taught by some of the pros I used at the time, there is the easy way and there is the other way. Just one man's opinion.