I remember a case a few years back of a hunter who had a map and compass, but walked off the map. IIRC, when he finally ran into some four wheelers, he was outside the boundaries of the map he was carrying. Even if you are very comfortable navigating/orienteering with map and compass, a cheap, non mapping, black & white GPS with a tiny display is a very useful tool even if you never use it until after you are lost. "Whoa, I walked off the map -- Doh!!!" Waypoint your truck!!!

Many survival situations start out with simply getting lost. The "hunter" who ate those worms is a recent case in point.