ORIGINAL: Edcyclopedia
It really depends as he walks, you know, one foot in front of the other.
If the furthest shoulder is back when you hit with your arrow, you risk a shoulder shot which could lead to the arrow stopping in the shoulder and not having an exit wound.
So a few variables come to mind and have been mentioned...
Degree of angle, height of your tree stand (assuming your in a tree) and where the shoulders are when you release.
I agree with this....dont just aim for the opposite shoulder, it may mean you would catch one lung sometimes on sharp quartering shots. Instead, in your mind draw a line between the centers of each shoulder, running right through the chest, and aim for the midpoint of that line. This will be as dead center as you can get.