I haven't done the estimate, but if there are several people stranded, it seems to make sense to split up to improve the overall chances of survival if the odds of being found are unreliable (all eggs in one basket and such).

Please also note the selection bias, where the happy ending stories (the person who left the car quickly found and brought back help) do not get nearly as much publicity. Presumably there are public stats available, if anyone here can find them.