I mix all songs in the same project. Easier for me to check everything twice, I don't have to switch around projects. Easier for the automation rides too, I start at the first song, then ride everything, then little manual tweaks, and done.
I use normally 3 projects per album.
1- MAIN PROJECT
Where I put the edited bounces, where I setup the programmed drums / synths / etc.
2- INSTRUMENTAL
Where I track everything that is external instruments (DIs, acoustic guitars, etc.) AND edit my stuff
3- VOCAL
Where I track everything that is vocals. I first make the screamer make a small part of the song, with "guide" overdubs, and I make a quick first mix multiple separate tracks that works for the vocalists voice. Then I create a "tracking" track where I record the vocals straight there, edit the takes immediately after the vocalist made them, then put the take in the right track. This way I already have an idea of where to create doubles, etc.
At the end of this I just transfer the vocal track settings in the first main project and voila, ready for automation and last minute mix adjustments. Helps me keep everything clean, and I work real faster this way instead of getting lost in the 523083 tracks I created for this and that. Cubase folders/group tracks and the possibility to hide MIDI tracks in mixer is great for this too. I found out I work real faster, and REAL better when I can find what I'm looking for in seconds. Since I started organizing my projects like that, my work is so much easier.
Yeah, this is, at least in a part, the way Joey deals with it, at least on the vocal tracking part. But heh... I tried it after seeing it could be dealt this way and I loved it. Can't help but using a trick that works.