Jagged Rocks on the Perimeter

[GG]

In tracking, you should get as close to 0dB as possible without clipping. This is to ensure you're getting as much of the 24-bit resolution as possible. It's admittedly hard to do, since even top musicians don't have precise control of the dynamic range of their instruments. This doesn't affect what the mix engineer has to work with. The mixing environment is a completely different system from the recorder. All he needs is nice, clean tracks. He can start mixing with all of the tracks pulled back. The extra 6dB you're talking about is left by the mixing engineer so the mastering engineer will have some wiggle room. It isn't affected by what you do in tracking either.

That's not correct at all. They should be peaking at around -6db. 

I do the engineering, the mixing and the mastering. Even the final mix needs to be peaking at -6db before you send it off for mastering. That's so the mastering engineer has something to work with when applying EQ, dynamics processing and leveling.