there are a couple of ways i judge 5 yards its about the width of a parking stall at wally world or food lion and second way is i just know how far i will go in 5 steps.
at any rate its not something that will come to you unless you do it all the time.I catch myself judging distances in stores, parking lots just anywhere i happen to be at the time. its kind of automatic for me to do it. and where yu need to be is catching youself doing it that means you were doing it and not realizing it that is when you can be very accurate.