The whole trigger discipline thing is a load of over hyped internet crap. never heard of it till 10 or so years ago. Ive been around shooting and guns my entire life and have never witnessed or heard of an AD or ND due to someone having their finger inside the guard. It was SOP while on patrol, be cognitive of what your doing at all times,ESPECIALLY when you are holding a firearm. If you cant then don't even touch or handle a firearm

Every posed picture taken while I was in the Corps has someone with their finger on the trigger, along with WWII era pics you never saw the straight "look at how safe I am" finger