This one depends alot on angle, distance, terrain. Like it best when they stand up or I can make them stand and zip.
Regarding the head shot, shotting a Matthews Black Max few years ago, cranked one in the head by mistake, long story, deer dropped in its tracks like a lead balloon. Shot a hog one time that was charging me, right between the eyes, he veered off, but never saw that pig again, looked like a unicorn going through the woods with my arrow sticking out of its head. Several years ago, on a steep angle up, single lunged a big cow elk and hit her spine, she dropped in her tracks rolled down almost over me stopped in dead fall and begin barking in distress without stopping, had to shoot her again in the head at point blank, took her out immediately, but was one of the low points of my archery hunting. Anyhow, some of those times where things didn't quite go right, fortunately there are alot more double lung quickies that went right. So, back to the point of this thread, from these experiences, I won't shoot unless 100% confident in a double lung. Have drawn 3 or 4 times on 340 class and bigger bulls in the past couple years, but never released cause something wasn't quite right.
Good hunting boys.
Johnny