I have purposely taken only one head shot in my 40 years of hunting. It was last day of the season, small doe right on the trail and only 15-20 yards away. Peeking through the trees and limbs the only shot I had was quartering away behind the ear/jaw. The deer had no idea I was there, and I had a rest against a tree with my 243 which was my go-to gun at the time and I had ultimate confidence.
Not sure I would do it again, but it worked out fine for me that one time.....
But for all practical purposes I want a easy heart-lung shot or I will let the deer walk. I astually let a monster go a couple years ago becasue I had a little brush between me and the big buck. I have made a couple bad shots in my life and I would rather not make any more.