The way it was explained to me is that the collar should be used at an extremely low level, just enough to annoy, not scare or hurt. The idea is to teach the dog that obeying the command turns off the annoyance. You do this by "collar conditioning" which is a long and careful process. And you never use the collar to punish, only to reinforce a command that they already know.
We went to a high-up Retriever Guru seminar (Evan Graham) and Shelley was the guinea pig for a session of collar conditioning and teaching the command "Come!" She never yelped or jumped - the typical collar (TriTronics) has 15 settings on low, medium and high for a total of 45, and we never got her above a low "2" and settled on a high "1". I sometimes bump her up to low "2" again if she's really jazzed.
I tune her up once every couple of weeks, and she comes like a shot.
Since Max has already had bad experiences with a bark collar (which does really hurt) he may not be a good candidate for a training collar. But we do have plenty of people who use them on Goldens - but very carefully.
Well, your trainers obviously are more expert than mine. I have a TriTronics, although it has 5 settings. It is a few years old. My trainer was adamant about setting it at the HIGHEST level so that the dog would stop in his tracks. I HATED it, so I have an unused collar. She was mainly worried that the dog would run in the street and get hit by a car, or tangle with a deer and get hurt. But, I didn't like it at all.
The video and instructions that came with the collar (and several other videos I purchased) were not really clear enough for the novice. It is really hard to get them right at the instant they are doing something wrong. LOL. I gave up.