I am all for chat and I do like to discuss a lane once it has been shot (out of earshot of the next group) - I do like a bit of banter as well + will always try to pass on help and advice when shooting with someone. This advice is usually in answer to questions asked and not to watching them shoot.
Any problems with their technique could be passed on after the last shot is taken and the course has been finished.
One person had a problem early on in comps and as we shot the course I talked them through what they ate / drank before a comp - it turned out they liked a couple of coffees just before shooting but found they struggled for the first 5 or 6 lanes of a shoot. I pointed out that the coffee could be the problem and that they should spend some time at their club to see if this was the case.
So - I suppose it is coaching but it did not directly influence their result on that day.
I am all for bringing people into the sport and passing on information to help them improve - it just has to be done in the right way - at the right time.