Usually I do two complete passes and the third pass is from the jawline down, with lots of blade buffing and J-hooking over the most common trouble spots. Usually I need little if any additional touching up to achieve a DFS every time.
A couple of weeks ago I tried doing two passes and calling it good, but I was spending so much time paying special attention to ALL of the spots I've had trouble with in the past that it was actually taking longer than going ahead with the third pass.
At first it was four, then it was three, now it is two. I've found my ability to get a good shave has vastly improved and as such have managed to reduce my standard shave to two passes. I still do more on the weekend or when I've otherwise got time.
Three passes for a BBS shave. I tried to do two passes only and I really wanted it to work out, but I just wasn't satisfied with the shave and went back to three passes.
Generally two with a DE, sometimes one with a sharp straight. I prefer going easy and feeling nice at the end over a bunch of passes that leave me burned. I pretty much avoid ATG passes these days because they don't leave my skin feeling happy.