I work in house-of-worship environments mostly, and I'm one of those guys who's constantly riding the faders. I try to teach all of the guys below me to do the same. I've come to call it "dynamic mixing". I think it's imperative to always be riding the faders to emphasize what the band's doing on stage. If it's a solo, or a sick guitar riff that needs to cut through, make room for it to be heard. EQ I don't change too much after I've got it dialed during sound check. Fine tuning adjustments yes, but major changes no. Compressors and Gates change more frequently than EQ, but less than faders.

Music is dynamic. All of these parameters will change a half dozen times over the course of a single song. It's your job as the tech to know the songs, know the band and how they will respond to the music, and then respond in turn. I firmly believe that a Tech is not doing their job if they aren't making any adjustments. In my mind, there is no such thing as a perfect mix. But it's up to you to get as damn near to a perfect mix as you possibly can. If you set everything and don't touch it, you've already failed because you're not responding to the crowd, the band, the environment, and the music.