There are certain parts of the routes I sign which I have never been over, even when road learning I had to walk along the track because there are no planned services along there. Obviously this requires route refresher training, but even that got knocked on the head when Network Rail refused to let staff walk the track at that location anyway.
Its much like if you drive the same route to work every day in your car, you know where you can speed up and overtake, or those bends that are sharper than they look. Drivers are going up and down usually the same bit of track day in day out, it would be hard NOT to know where you are! Having said that, sometimes if the siggy calls you up for trespassers or whatever at XXX user worked crossing in the middle of nowhere, can take a few mins to figure out where exactly that crossing is!