Here are a few key spots I look for. Mark is definitely a better and more dedicated shed hunter then I, but here is what I look for. Find where they are feeding and bedding look in both of those spaces and to and fro. Also anywhere like a creek crossing or anywhere where they go up and down a hill can be good spots. At the base of the antlers the bone starts to fracture. Kind of like a loose tooth. Any jarring or sudden movements can cause the rack to come looser or drop. Hence, the Creek Crossings and Topo variations tip. Heck, in the Suburbs I have even found sheds on the sides of roads where the trails cross the street. From them scurrying to get across the street and having them jump the snow banks on either side. I have found 2 sheds this way.
Bucks spend most of time in their bedding and feeding areas, therefore those are best spots to start at. I’m guessing Mark puts in his time and just don’t hit an area once and forget about it. You need to keep hitting those key spots every other week. Lastly, I also bet Mark puts on quite a few miles each Spring. Hope this helps.