The super hyperactive communities are part of why I keep leaving and coming back. I've found that the overactive games where I can't keep up reading/posting are bad for me writingwise, and the super quiet games, where I feel like I need to put in a LOT more work to drive the plot are also bad for my writing. So I've drifted towards the mid-level games where I don't feel guilty if I take some time off to write, but there's still plenty of activity to go back to.
Another thing to think about is bringing a notebook/laptop to places where you can write where you wouldn't normally game. Like sometimes I'll make wordcount on my lunch hour.