I'm not sure where this would fit, but I tend to be pretty monofannish for roughly four years or so, then I move on to the next thing. I may dabble in other places, but I stick to my one show/band/whatever. And when I'm done with a fandom, I'm DONE. There is very little going back. If it's a tv show I'm being fannish about (currently SGA), my fannishness wanes as the show begins to inevitably suck (hello, Buffy Season 7, I'm talking about you) and pretty much ends when the show is over. I see no point in being fannish over something that is over, done, kaput.

:)