Should you find yourself up the proverbial creek, how long do you think that the SAR teams will keep looking for you? It's longer than you might expect. Yes, it does depend on terrain, light and a number of other factors, but ultimately, they don't take a casual look for you and think "bugger it", even if it's just the one person.
On a recent shout, between the lifeboats, the fishing boats, the choppers, the coast guard and the public, the search for a chap who was thought to have slipped on the rocks did not stop for 21 hours (with only 4-5am not covered) until he was found though everyone was prepared to keep going.
So how long do you think it would have carried on had he not been found?