I had a conversation with a guy from San Diego at Iguazu Falls during which I mentioned I was checking things out for next time. "You're coming back here?" he asked. He told me he generally didn't go back to places after he'd visited them.
While there are places I find don't like, I do try to give them a chance later. They just drop farther down the priority list. And when I have bad experiences I try not to repeat them. It's true though that the idea of a "once in a lifetime trip" is alien to me. If I like a place, why wouldn't I plan to go back? Travel is easy nowadays, and getting easier every year.
It does depend on what your motivation for going places is.