In truth, I almost never look at the track meters except to make sure nothing's hitting red. Most tracks peak around -12 dB but I'm not obsessive about it. Exactly
where your track peaks fall is unimportant,
as long as what they sum to stays reasonable. It's not like the tape days, when track levels profoundly affected sound quality - with digital, you have an enormous acceptable range.
What counts is what all those tracks add up to. On the master bus I like to ideally be under -6 dBFS pre-limiter, but it depends on how percussive the material is. For highly-percussive stuff, I don't sweat -1 dB peaks on kicks or tympani. The important thing is the peak-to-average ratio (crest factor); I want to see those drum hits rise above the fray.
Post-limiter depends on the target medium: -0.5 for CD and FLAC, -1 dB for MP3. But nowadays I pay more attention to the LUFS meter (iZotope Insight), setting a target of -13 or -14 LUFS for most things.
Admittedly, I probably do not represent the average user, though. I prefer the final limiter to be doing as little as possible - ideally nothing at all.