posting advice sought

how aggressive should we be posting messages in the forums?

i tend to be conservative at posting messages - posting a message only if i am downloading a video or can comment on a video that i have already seen. but sometimes i see aggressive comment-ors who seem to post messages in every possible forum. now i like participating in the discussion as much as anyone else, but i've always thought it better to only post when i have something worthwhile to say.

how often do you post to the forums and how do you decide when you've come up with a relevant post?