Never solely rely on anything electronic. It is not if they fail, but when they fail. Ever back up data on your computer? But, once hiking into a canyon near Prescott AZ, I soon lost the trail as dry run off paths looked like trails. Anyway when I got down into the canyon floor the GPS helped me figure out where I was. Next day as I started to hike out, I also followed a dry river bed and the trail was not visible. Suddenly I came upon a vertical wall of smooth rock, once a waterfall. I had to climb up out of the river and soon found the trail, but where on the map was I? Again I used the GPS and found that I had not yet gone off my map, so I knew I was okay as the trail was helping me complete a circle. Supposing I had not had a GPS, just my map and compass. Guess what? I would have been fine and able to locate my exact position. Why? Do you know how a steep vertical waterfall shows up on a contour map? When contour lines cross streams or rivers, they loop slightly uphill or upstream. Water runs downhill, right! So, as the line crosses the stream it shows which way is uphill or upstream. But, if a waterfall is there the line goes straight across showing a straight drop down. That is where I was. No GPS needed as long as I had the topo map! Without a compass one cannot walk in a straight line for very long. You will start to walk in a circle. Try it next time you are on a playground field, a soccer field, etc. Put on a blindfold and try walking in a straight line. Have someone sighted next to you to keep you from walking into danger. It won't work if there is traffic or other noise to help keep you oriented. You will soon start to curve off to start what would become a circle. In the woods without a blindfold, pick a compass course to follow, then put the compass away. In ten minutes time you will be way off course. That is why I never hike without a compass. Get off trail and you will walk in a circle without a compass. It has happened to me several times, once even on a small island in Maine, Roque, Is. Once at night when I was trying to stay on course, following stars and only occasionally checking my compass. I came upon fresh tracks in the snow and soon realized they were mine of only 20 minutes ago. It happened again when skiing, came upon my tracks again, and another time while hunting. Came upon the same road I had started on half an hour before. Never thought I was walking in a slow circle. Even while hiking the AT in NY, I had to use a compass to get myself back on the trail. Hike in the fall with leaves on the ground. It is easy to find yourself off the trail and without a compass you could soon be really lost. Be careful taking short cuts through the woods if you do not have a compass. The Army dropped off a guy in Alaska by chopper where there was only snow, no landmarks. They pointed him north, left him alone an hour or so. Guess what? He walked in a circle.