well the idea is not to record everything at full volume, gain...whatever. However, I've worked with engineers that love to clip the #$%# out of everything.
I think the best method that was worked for me is to develop an organized sense of events. The idea is to make things easy for mixing. So when you're dealing with alot of tracks (maybe 24-124), you're going to need headroom.
Essentially you leave your faders flat and adjust your gain trim. You get relative balances within groups and the idea is to try and make it sound like a song right from the get go. If that means that your lead guitar is -12 instead of -3, then thats fine. The idea is to get balance, not to max out every last track. It's ok for things to show up really low if that's the intended purpose.
So for example,if a professional track engineer sends you a session you have to mix, your first instinct is to set your faders flat. Maybe a little higher than mid way (to prevent distortion). Right off the bat, things should sound generally balanced and not out of whack in relation to one another. Plus it's ok for the mix to sound low, you're job is simply to mix and create blends. Loudness is a post mix thing. You might see values like(for the sake of examples):
kick & snare peaking at -3dbfs, OH, toms & HH peaking at -6, bass peaking at -6, guitars at -8 and vocals at say -4. You wouldn't try to normalize everything to get it close to zero. Your job is to preserve that balance as was intended in the tracking session.
If it was a good tracking engineer, he actually made your job really easy as a mix engineer.
So essentially, the idea is to preserve the holy balance. The better you can do that from the beggining of the food chain, the better your mix will sound. So even during recording, you're acting as a make shift mix engineer.
But really, above anything else, I think it's very comforting to know that there are a million different techniques in this world that work. So its because of that fact that I'd rather use my ears than memorize any numbers or specific steps to doing something.
75 years ago they could of told you not to max out analog because it sounds horrible. Then come to find out that it becomes a cool effect in the 70s, 80s, 90s etc. So alot of it has to do with trends of the industry and the kind of music your mixing against. It's a total judgment call.