From my experiences, a deer killed by a hunter, either with an arrow or bullet has already bled out. I think this is the main reason they expire, especially with good shot placement. When the deer is field dressed, most of the blood is removed with the internal organs. When shot through the heart lung area, the chest cavity is filled with blood as all the blood is passing though these organs on a continual basis. I don't think that cutting the neck is necessary. It just adds an extra opening to allow bacteria in that can cause meat spoilage. Any extra blood that is in the muscles will drain out when the deer is hung. I prefer hanging my deer with the head down. This allows any fluid to drain out though the neck and not though and over the hind quarters. I also haven't observed much blood pooled under my hanging deer, suggesting that most of the blood has alrady been removed during field dressing.