The problem with the "faders at unity for setting gain" approach is that if you teach it to someone who doesn't understand the rest of the signal-flow, they might think "I want to keep my faders around unity so I'll adjust the gain as I go." We all (I assume) know this has bad ramifications for monitors and pre-fader effects, but for someone just starting out at mixing this can be confusing. Believe me, I've walked into a situation to settle a mix before stepping on stage to play bass with my artist, set the monitors up and got a decent mix, then when on stage the monitors went stupid because the "engineer" kept fiddling with the gain knobs instead of using the damn faders.
I have always done the opposite: set gain with fader at the bottom, then raised it up to the level that sounded appropriate for the situation. My faders wind up all over the place, usually with the vocals at Unity and everything else mixed to keep VOX on top.
I mix musicals twice a year using the same approach, so all the actors voices start at unity and the orchestra hovers around -10 to -30 depending on where I want each instrument in the mix. I have Groups set up for Orchestra, Lead actors, male ensemble and female ensemble (and one more for kids if appropriate). Mic-check with actors is just for making sure placement is correct and adjusting gain if there is an issue with their voice that day.
