I think I overthink everything too much!
After taking my time setting up the eCollar, fit and base level of stim, the first lesson lasted only 5 - 10 mins before I had a recall from stim alone with no prompting with the leash. Called that excellent and gave Jazz some happy play.
It had been my intention to practice recall until it became automatic, but with Jazz it seems to be better to get out into real situations as soon as she understood what was required of her. She is also responding to the second to lowest setting. And wow, what a difference! Her general attitude is much more attentive, and I have only had to use the eCollar a very few times. We don't always have the collar on, and sometimes it is on but I don't need to use it. Today we went for out first morning walk out where the roos and cattle are with her off leash. She did head out after some roos, I called her and then gave her +2 stim and she came tearing back to me, flat out. The same thing happened when we walked near the bull, (who just stands there and looks at her!) On the way back I deliberately went past the bull again and called Jazz to walk beside me, and there she was, not even looking at the bull. Same for roos.
So, it is all very simple really. No drill sessions, no traumatised dog, just a very simple, very effective way of giving your dog a tap at a distance at EXACTLY the most effective time!
My thoughts are that I could have been using an eCollar much earlier, but having her training to a level where she understands what I am asking without a doubt and using a stim just to reinforce obedience has made things so easy.
Just a funny side effect was that we were around the place with a thunderstorm on the way and it let loose a loud and startling flash/crack. Made me pull my head in, and made Jazz come racing over to me and plant her side against my leg, almost trying to climb right onto me. Totally different reaction than before eCollar training!