I've always felt you need to wait with rifle hunting as well, although I think the wait periods are even longer with archery. Obviously I'm going more on what I've heard than what I've seen in person. But my sense is it can take a long time for the broadhead to work its way around the cavity and cause enough damage for the animal to bleed out and die - it's not like there's a big hole blown out the exit like you'd see with a rifle. My cousin's elk (pictured in my story) was a good example. He shot it quartering away behind the shoulder and his broadhead buried in the lungs. But it took that animal a good hour to die. Every time he'd move his leg, breath, lie down, etc., that broadhead moved around and sliced up the inside of his cavity just that little bit more. By the time we found him, the broadhead had actually worked its way back out to the skin on the entry side (as you can tell from the pic), and there was a whole lot of damage on the inside. But it still took him a long time to die.