I think the main factor is how most people now days are never confronted with truly stressful experiences and forced to deal with them. It’s a learned skill that goes way beyond hunting.
Mine comes after the shot, but not always. This years buck ran in so fast no time for anything other than focus. After the shot i started to shake alittle what a rush.
I've shot a boatload of deer with my gun and I still get an adrenaline rush when I've got one coming in I know I'll be taking a shot at. Seldom miss (doing whitetail deer drives).
I've blown my load on more mule deer than I'd like to admit during archery hunting....
I'll have to do more reading on it to see if I can keep my shit together this year on mulies