In the very final point in the mastering stage, sure. But during mixing, I'm usually at around -30 to -24dBRMS with around an 18dB crest (so maybe an occasional peak of -6dBFS or so).
And you're not going to be "bringing it up" by any means --- If you have a bunch of tracks *peaking* at -12dBFS, you're going to have to attenuate many of them during mixing to avoid clipping the 2-buss. I tend to track somewhere around where things are going to sit in the mix (so I might have a bunch of incidental percussives at -40dBFS, overheads at -30dBFS, etc., etc., etc.) and more times than not, I'm stil attenuating half the source tracks to keep some measure of headroom.
That said, if you're summing digitally, you're almost always going to peak higher than your average track's peak level... That's just going to happen "naturally" (for lack of better terminology). You'd be fighting it - or at least, doing something very unusual to have something other than that happen.