I turned back 50 hours of FFXIII because I missed a weapon (which I could have bought, I just didn't like the idea of having something no collected). I don't like things to go missing.

Which is part of why I hate games like FFXIII which have treasures that are permanently missable. You should always be able to go back and look around at an area from long ago and still find an item if you never found it the first time.