there's two angles here. 1. "how do you deal with support" which is to say, how do you respond to potentially hundreds of questions a day and not drop them, and 2. "how do you decide how much time to spend on support, vs. other things"

As for 1.

I use RT, but frankly it doesn't work that well for us. We're all primarily email people. Nobody wants to use the web frontend

I've worked other places that just used a shared IMAP box; if you were dealing with a customer, you pulled them out of the shared IMAP 'support' box and put it in a shared box by your name (that way, if you were sick the next day, someone else could cover for you) and dealt with it. I'm seriously considering abandoning rt for that solution.

As for 2, personally, I think I often spend too much time talking about stuff rather than doing stuff. But, talking to people requires a different kind of energy from coding, so I'm not so sure that it's eating into productive time. I mean, for me, it's almost a social break. (I mean, if I did it more, it wouldn't be so much of a break; I'm at least moderately introverted.)