With the e- collar I also think it depends on the dog and the trainer and as the study concludes for that type of training and probably with dogs that had already passed all the selection tests regards to temperament.
I had a phone from my neighbour who also trains working dogs as trialing dogs. He has a very timid kelpie who is a good worker but can be difficult due to his nature. I have observed them working together and my thoughts were he was too impatient and hard on the dog and was pushing him too fast. My neighbour was having trouble with his stops and decide to use an e- collar as some people do, hoping to get quick results.
Well after that the dog flatly refused to work for him so he was aking if I would take the dog on as he though he might respond better to my methods, or he was going to have to shoot it. I have 2 other working rejects I am training and didnt have the time. Fortunately I knew someone just looking for a working dog and wasnt interested in trialing - much better set up for this dog.