We used to call self extraction routes "Panic Azimuths" in the military. The basis of them were that, when SHTF, its one of four cardinal directions, and a landmark you are HIGHLY unlikely to miss (be it a road, town, country, etc). This is something I leave when I go off on my own, but havent had to use it as of yet. I usually choose a road, as you cannot really miss hitting that. As long as my panic azimuth will guarantee I hit it, the distance doesnt really matter. On paper, it sounds like a decent idea; as I havent ever had to employ it though, I am not sure of the practical use; using cardinal directions works great with even a button compass, and even with terrain variations, you SHOULD be able to get to your RP, but I am SURE mr. Murphy is waiting there for you....