This sorta thing happens way too often for me. Regardless of what game it is, its length, or my love for it... more often than not I'll get distracted by another game once I'm half to three-quarters of the way into it.
I'm on chapter eleven... don't know where that falls in terms of discs since I'm playing on PS3.
I am not even sure where I left off to be honest. Work and school had me wanting to put my head through a wall and then by the time I felt like playing games again, I picked up something else and FFXIII/RE5 got put aside.