I've had to track more than a few in the last several decades, but I found most of them. And once I watched the son of Dad's best friend gutshoot a doe, after which the kid took a brief look for blood and then just up and left. He didn't know I was watching. I tracked the deer and took it home and was in the process of skinning it, when Dad showed up. Made me give half the meat to the kid. I wouldn't have given him diddly for that poor performance of his.
Anyway...I've found that good old fashioned toilet paper is a great help when tracking in daylight and dusk. Severely wounded deer, at least in my experience, tend to leave in a mostly straight line. Where you find blood, hang a small bit of toilet paper (the bright white stuff). If you lose the trail, just turn around and find your path, as outlined with the TP. In dim light the white TP shines brightly when hit with a flashlight and is easy to spot. It really is helpful, and then there's the other use...
And unless the deer drops straight down at your shot, wait for 10 minutes or more before starting to track. Unless alarmed, the deer really doesn't know why it's getting weak. It'll lay down and bleed out. But if it sees you immediately after getting shot, it'll run till it drops, which might be quite a ways.
When I was young I could track a lizard across dry rocks, but as I've aged, my skill level is much lower. Therefore, I'm more picky with the shots I take. I think they call that "smarter".