It can vary, in VIII I took over 100 hours my first time but then again I left my game on through out the day and I wasn't playing so that piled on the hours. My second time I think it was about sixty hours or less which was much better. In VII I think it's about fifty or sixty so far, I still haven't finished it but obviously it takes a lot longer if you decide to do all the side quests and what not.

I'm not a perfectionist but I like doing what I can when it comes to collecting all the optional stuff such as Materia and weapons etc.