Early in my career I was stationed on a WMA in northern Indiana (Kingsbury FW Area). About 1,000 of that 6,000 acre area was off-limits to the general public and for any hunting due to the possibility of unexploded ordinance. So this area was refuge.
Whenever deer hunters, shot deer that ran into this no-go zone they had to come to the check station and fetch one of us to track the deer. The hunter wasn't allowed to go with us. (Too many hunters violated the no-go rule though and entered this area on their deer's trail -- often just far enough to mess up the trail and make finding their deer more difficult.)
I remember times when we actually had different blood trails cross each other. We got lots of tracking practice. Also saw a lot of amazing deer!
I use actual tracks more often than I realize sometimes. I ignore the tracks as long as I'm finding blood other than to note, if I can, the size in case I need em. It is common to find "escape tracks" where the deer was standing when the arrow hit, usually before blood but like others, there will be hair there but often very difficult to see. Of course if you have lost blood and are checking multiple trails sometimes there will be no fresh tracks on those trails. As obvious as it sounds, the deer didn't go that way! So focus on ruling out other directions as you try too recover the trail.
I remember tracking a gut-shot deer (scored 146 something)for a friend in the early 80's. When that deer left a narrow woods where he was shot and entered a large alfalfa field we had not yet found a blood trail. However, we had followed tracks to the alfalfa. Then on hands and knees we could feel the ground (in the vegetation) for those tracks. We made it 50 or so yards but it was way too slow and unsteady going. I noticed a brushy right-of-way 200+ yards or more out front in the general line the deer was going across the field. So, I went way around the supposed trail and went to that right-of-way (utility). Bingo... we found first blood right there on tall weeds in that right-of-way. The deer went through another small woodlot and then into standing corn. I called the hunt off that night because we were trailing him by disturbed leaves because blood was so sparse. We found him about 30 yards into the corn field, the next morning in just 15 minutes. I'll never forget how his trail starting wavering (totering right and left) at the very end.
I like tracking with another person although most of my tracking has been solo just because I hunt alone. One person will stay at last blood (usually the shooter because he is too wound up too take time looking for blood) while the other follows the blood-trail. Of course there are all kinds of tricks of the trade....path of least resistance and using tissue or flagging tape to record a path of travel which can sometimes be helpful in projecting where the deer likely went. It is very possible, I suppose due to lots of tracking, to get pretty accurate and figuring where the deer should have gone.
Except for the first 10-30 yards after a fatal hit most deer I've tracked avoided going through brush, piles of limbs, i.e. places they would have trouble negotiating if unwounded. Of course the first mad dash after a lethal hit can send a deer running into trees, etc.
I remember tracking a bear in Ontario, well after dark by the leak plants it's paws bent or broke. I also remember on one of these trails hearing a bear ripping into our bait on the back trail. That was erie!
I think it is a terrific idea for hunters to volunteer (without creating the crowd Kirk so rightly alluded too) to help trail for the experience.
The blood trail is SO important. If the deer is bleeding and you stop finding blood, it is almost always there but the deer changed direction and you have simply lost it. Resist grids and half-circles as long as possible trying to find the blood trail again. Once the girds, half-circles, and meandering searching begins the chance of destroying the blood trail increases.
I hate to remind myself but I lost a nice buck a half dozen years ago. I was certain I saw that buck turn left about 60 degrees about 50 yards out. The hit was just below the top of the back, my side, angled perfectly down, and forward towards the opposite shoulder. I didn't have an exit wound and no blood to that point. I didn't even think to go right because of what I thought I had seen. Eventually after hours that night and the next morning we (I!) lost that deer. He was found by my buddy 3 days later just 50-60 yards to the .... right. Very dumb mistake. I was sick and punched my tag right then and there.
Between us we had 80 years of bowhunting and recovering many dozens of deer. Had I made full 180 half-circles instead of 90 degree quarter circles to the left, we would have found that deer that very evening. The real irony, is the deer was found a few yards off the very path we normally take to and from that stand! We didn't take the normal path out that night or in the next morning because of my thinking the deer was too the left.