I've used strategy guides for Crisis Core and FF III. And Pokemon And Lost Planet And Battlefront II And KotOR and KotOR:II and many other games.
No, I just do it the first time I play through. Can't be assed to replay Final Fantasy VII just to get things I could have gotten on my first playthrough.
Understandable why you would do that for FFVII. I did that on the second run since it was a while after i played it for the first time n' didn't have a guide. xD