Army Land Nav "checkpoints" or markers were 1 foot square concrete pads set flush with the ground. But certain courses were used so often that there were trails connecting them all. Also, when you were doing a land nav problem with a group of 100 or so folks, you'd be at your marker, shoot your bearing and see a knot of people standing the appropriate distance away. So you'd put your compass in your pocket, walk over and join them. This was in the reserves and the course was for reservists. We heard stories about the land nav course for Active Duty Infantry E-7's. Each "checkpoint" had 4 markers arrayed in a square within 10 yards of each other, so accuracy counted.