Assuming song length averages about three to five minutes, I'd expect eight to twelve tracks. If most songs are seven to ten minutes, or more, then four to six tracks is probably enough. I guess I'm part of the "length matters more than number of tracks" band wagon, but there are certain conditions. I generally don't appreciate it when songs are too much more than ten minutes though, because sometimes I don't have that much time. Listening to Persefone's "Core" album was quite a chore because three of the four songs on that album are over twenty minutes long and I had to make time to listen to each song, rather than just playing the album when I wasn't busy. I still haven't found time to listen to Devil Doll yet, because three of the five albums on my computer contain only one song lasting anywhere from an hour to an hour and twenty minutes. There's no way I'm going to have that much free time without interuption while I'm at college.