We learn from experience. Make mistakes and learn never to repeat them. Hindsight.
But sometimes people find themselves in unusual situations. Things which are out of the ordinary. And when people find themselves in unusual situations they fall back on experience and try dealing with the unusualness in a usual way. Because by their very definition, unusual situations are things which don't usually happen, which means that there isn't anything to really fall back on.
The smart thing to do would be to learn to deal with unusual situations the way they should be dealt with - unusually. And in the process learn, grow and evolve. To find a new way to deal with a new thing.
If only we were smarter.