Good topic Randy:)
Just a few points I got to add to what's already been said. Clotting doesn't take long to begin and often can be found within the first 150-200yds into a track. Hunters often mis-identify clots as tissue or organ chunks along the trail up to the first bed when in fact it is the blood already clotting on a marginal shot. A false hope then sees the hunter marching on toward the bed earlier than they should. Waiting 1/2 hr isn't long enough. Before that buck beds to stop the bleeding, he'll most likely stand to survey his surroundings for aproaching danger for 10-15 minutes before bedding (indicated by pooled blood before the bed site).
If it takes you 15 minutes to bump that buck from his bed, in all reality he's only been bedded for 15 minutes. That's plenty of time for him to clot up an external wound, get to his feet and leave no sign from the bed to be followed while still bleeding internally extending your track farther than it may need to go or could have ended.
Blood color, hair color and length of it at the shot site(yes there are about 6 different combinations of white, tan, grey, black and brown of various lengths on a deer) to narrow down the impact point, bubbles and their size can tell if 1 or both lungs were hit.
It's freaking crazy the amount of clues a good tracker can discover to make you feel like a real greenhorn on the trail of wounded game. If you ever get the oppertunity to tag along on one of these recovery missions I highly recomend doing so. The dogs are amazing to watch work a trail even without blood, they pick up the individual scent of the interdigital gland of mortally hit deer.
I think from what I've experienced here on shots I'm not sure of impact, I'll be heading home for a few hrs to rest up for a potential drag instead of wasting time chasing any wounded deer out of the county unecessarily.