I don't think it has to be every day, necessarily, but just consistently, no excuses when you're "just not feeling it" or something like it, plus not too much time between bursts of writing so that you don't forget where you were in the story and what you wanted to do with it.

Hmm, that's close to what I'm planning on doing, sort of. The thing is, I'm a writer by day as well, so by the end of a weekday, I'm usually out of most of my creativity. So I've decided to basically outline the hell out of my ideas during the week and then to write from the outline on the weekends, starting with smaller fic ideas or scenes and to build things up, as it were. I've yet to see if that works, though :)