Hi, Jeff. Oldster here with 51 years in the deer woods from NC to Texas, back to GA,most shots within 150 yards, many under 100, a few 300+, just recently started shooting long range. I've taken a few high neck firearm shots at very short range, with open sights, under absolutely perfect conditions, with good results, ie, drt. Regardless of ability, things can and do go wrong at longer ranges. Bullet flight time, wind, brush you can't see, etc. Bullets that are fine for conventional heart/lung shots can blow up on thick bone, or deflect away from the brain.
I laude you for asking this question out of honest concern, and also for deciding not to engage in head shooting going forward.
As members of a dwindling population of outdoorsmen, we have to ask where the line between hunter/sportsman and showoff/killer lies. Our future existence depends on it. To take iffy shots at long range, in my opinion, crosses the line in the wrong direction. I know that many of you practice tirelessly, and know your rifles/ballistics well, under actual shooting condotions. Your extended range capabilities are amazing and, due to hard work, still within the pale of sportsmanship, but a head shot at range just has too many variables to qualify.
No self defense gun trainer worth a **** recommends going for the head first if there is any other viable choice, and for the same reasons; lotta bone, lotta movement, even at across the room distances. Market shooting of game to sell is not, in my mind, hunting, and perhaps has its own rules of engagement, or none. My 2 cents.