"Proper planning prevents p###-poor performance" is certainly true, but sometimes Fate intervenes. On land, at least, a survival situation develops as the result of a cascade of poor decisions, eventually resulting in difficulties.

The classic survival situation arrived with air travel, where in one minute you are floating serenely above the clouds - minutes later you are on the ground in a very different environment - alpine, jungle, sea, Las Vegas, the Hudson River - you name it. Shipwreck is sort of an intermediate category, but land based emegencies usually develop gradually.

If the land based traveler is half-way well equipped for conditions, there is really very little gear that is carried explicitly for survival. Something like a poncho (good extra layer for cold and rain, as well as the basis for shelter), one or two alternatives for lighting a fire (the weight and bulk can be trivial), and a bit more water and food than you might think absolutely necessary. I emphasize water because most of my experience has been in arid regions, where H2O is gold...Not so much the case in the Boundary Waters of Minnesota.