I've killed deer with .50cal - patch & ball - conicals - sabots bullets, none required me to follow a blood trail. They hit the ground within sight.
2 years ago I shot a big 10 point buck with my 7mm mag. He ran like I had missed him. I walked over to where I had shot and there was a little hair and no blood. I started a circle search and found a small drop of blood 40 yards from where I shot.
Long story short, I found the buck 70 yards from where I shot him. There was a pass through of both lungs. So there no rhyme or reason to when a deer leaves a blood trail.
I also hunt with a bow and there's always plenty of blood.