MIXING is one thing.
MASTERING is another.
always keep the two approaches separate.
the idea of getting the best SONICS falls under the mixing category..
obviously, using software meters is 'close' at best.... so always be frugal/diligent/conservative with levels during tracking, to get the best sonics.
the idea of VOLUME on your final product, falls under mastering.
gain staging is everything in mastering..
there is a lot you can do before you hit the brickwall limiting required for modern mastering levels.
but EVERYTHING you do, from the individual tracking all the way up to the final dither, is connected to everything else...
and you really gotta know what you are doing to get it all to fall into place.
takes a million mixes, and a million master sessions, before you get really good at it.
and even then, you are always hampered by the quality of your gear, from the microphone to the treatment on your walls, to the definition of your monitors, to your understanding of gain staging from the very first track.
the problem with peaks at 0 db is well documented.
do some searching on mastering techniques all around the web, and you will see issues with 0db.
now, if you happen to like the sound of 'crunchy' masters, then by all means, flatten it to the wall.
it's an acquired taste.