But when talking about finishing a project, completely, mixed and mastered, is not the same as what the OP is asking about laying down tracks. I can lay down 12 tracks in an afternoon, depending on if I'm still writing the parts or already know what I'm going to play for each instrument.
It's the post production mixing and mastering that takes days or weeks. I think that's an important distinction when answering musaed's question (which I believe was asking about laying down separate tracks).
And for those who are laying down separate tracks for each drum piece, I'd highly suggest getting Superior Drummer 3. All the individual drum parts can be mixed within SD3, along with efx. Thus freeing up your Sonar tracks to where you only have to create one track for the drums. *just my 2 cents on that issue