I’m not saying that to be smart jwalker…….That’s how I see it happening. The dog is following the deer that is putting out blood and other fluids on the ground. On a normal track where I ‘m there 12-24 hrs after the shot there are just about always gaps in the scent line that the dog has to link together to progress it....we call it working a "check"…..Its not like a solid scent line through the woods….its more like dots and dashes from morse code. Being there on a track within an hour or two allows the dog to smell other scents that make it easier to link those dots and dashes together. However that also increases the chances of dealing with live deer. That's my opinion anyways.