J.O.
NEVER!!!!
You have hit on a loaded question thats for sure!!! Just cause a baby can go without food for 12 hours doesn't mean they should, and there are many factors as to why a baby wakes. I would hate to sit in my room upset and lonely and afraid and nobody come to me, at least as an adult if I am hungry I can get up and get myself something to eat, a baby doesn't have that luxurary he relies on the only person in the world he can count on.
Another parent offered a good book on getting your baby to sleep with having to let them CIO, take a look at that. If getting a baby to sleep through the night was supposed to be easy they would of been born into the world with the tools to do it. We are the only country in the world that seems to think it is Ok to laet a baby CIO, I just don't get it?!