I don't disagree with your conclusion - once every ten years seems fine. F4 have had their origin told more recently than that, though. And between older movies, cartoons, comics, and word-of-mouth, I think we would be hard pressed to find very many people (who would watch a Superman movie) who wouldn't already be familiar with (at least the basics of) his origin.The kid for whom this is their first Superman. I agree that origin stories get tiresome as you get older, because you keep seeing them, but for every movie there's a generation for whom that's their first. While you can do it too often, once every 10 years or so seems OK to me.