As far as "quality" goes, it doesn't matter .. digital signals and all...vs tape, where every bounce hurts. Though that is strictly technical quality of the recording , not nescessarily the quality of the sound to the listener (if that makes sense)...
It is a matter of opinion/intention, then, not good or bad. By this I mean seperation of sound... ie, if you mix a lot of track to one track before you apply effects then all tracks will have the same level and type of effects.. this is good if you want a homogenous sound...If you want a track to stand out more, it is better to run in through its own effects etc before mixdown so it keeps its own character... you essentially balance these two forces, creating a homogenous sound ( like people actually playing together in a single room) with making the individual instruments distinguishable (like different people playing together on different instruments). This is always the challenge with multitracking, to create a feel like a real live performance experience...
In the same manner... and I think in tune with G-, you also get seperation from stereo. So you often mix multitrack to 2 tracks, not one, to create seperation to distinguish similiar sounds or create a stereo effect. Though with a solo act, you can mix to one track... there is no need for a stereo seperation, though you can "spread" even a solo sound a bit... but that's a different story.
example: I have a percussion section with three conga players.
if mixed to one track, it becomes confusing, all three sounding like one drum. Instead I mix into 2 tracks with one drum in the "L" track, one in the "R" track and one in both. So in the mix (and final stereo .wav file) you hear three distinct drummers, one playing off to your left, one off to your right and the third in the middle, and the primary beat (center) and the synchopation are distinct and clear to the listener. You close your eyes and "see" the players located in space by their sound. It is very easy to "see" and instrument move as you play with a mix and vary the pan control for a track.
again, this is a matter of opinion, how much you want specific track/instruments to "stand" to one side or want them to "stand" together in the middle. You don't want a drum kit spread left and right like the conga example. And then you definitely want to apply the same and equal effects to the final two tracks.
anyway.. I'm no pro, so I might be all wrong as well... good thing to know. I'd hate to sound too confident.
