In reply to toasted: Speaking broadly, I don't think doing a problem once necessarily makes it easy to repeat. The example that springs to mind is Paul Robinson on the story of two worlds, on his first time round he dabbed a tree while topping out. Took him quite a few days of attempts to then re climb it sans dab.
That being said, once you've climbed something once you do relieve a lot of the mental pressure of the initial send which can make it easier. Id say the net effect is probably that the problem becomes slightly more doable, though not significantly.