The more lung tissue that your broadhead goes throughthe quicker they will bleed out, pass out, and thendie.

This doesn't necessarily mean a center punch through the lungs. It could mean a high quartering away shot that enters high in the rear of the lung, travels all the way through, cuts off the arteries in the center of thelungs and then exits through the lower front offside lung. That's a heck of a lot of lung tissue for the arrow to pass through and a tremendous ammount of bleeding that will occur.

The lower in the bodythe holethe quicker they will leave blood on the ground.