Depends on the critter. I have never found a whitetail shed, but have never gone to look. It's on my bucket list. Elk sheds for me are easiest doesn't seem to matter where, but I don't remember the last time I took a trip and didn't find one.
Deer for Eastside muley, bench bucks, and Blacktail in southern Oregon it's also a high percentage. Probably not quite as good as elk, but still average a find per trip or so. The "epic" days fewer tho. Low country Blacktail are like gold! With the dog I do better, but bucks themselves are so scattered and utilize such a small living space that time of year combined with vegetation and I think I'm at about a 25 percent success rate. Maybe 1 every 4 to 5 trips. BUT if I can find the buck before he drops or stumble on an area I know is a bucks core area, my odds of finding that deers sheds are very high. Moose, I have never gone to look but have stumbled on several incidentals. So feel lucky!