SNIP
im sure there are times when a little more penetration would be helpful, but im not bear hunting.... a deer is only about 12" wide, so any more than 12" of penetration seems a waste...
I suppose if you give up the quartering away shot that your bullet selection is pretty safe, but if you take that shot and misjudge the wind or an animals speed and hit the onside rear leg going in you will probably wish that you had a bit more penetration.
One point that most folks don't consider is that bullets cause damage by going fast! While the bullet that exits the animal can't do any more damage after it leaves, while it is inside it creates MUCH more damage if it also exits fast! Explosive bullets are slightly different, but their fragments are not.
Take a "perfect mushroom" that many love.
If it stops inside the animal, then the last few inches acted more like a field pointed arrow, and did very little damage for the last "x" inches!
Now if you shoot a radar guided bullet, then use only enough energy to reach and penetrate the heart and then stop
edge.