markers are there to make sure you don,t miss a wire, i wouldn,t use them if i only had a handfull to check , but if your on with a couple hundred snares over a large area , then markers are essential, it also depends on the the terrain, even on fairly open ground its easy to miss an un marked wire never mind some of the stuff i set snares on
at the end of the day its personnel preference, but try explaining to the keeper or a farmer when they find summit in your wires a few days after you pulled them
and lamperman , less of the old, i,m still a young buck at heart