From what I’ve read, you should not aim at rising rank through quantity posting, but rather qualitive posting. That it, it is way better to post less and let those post be meaningful, that post a lot of one-liner unthought comments.

Activity is the formal requirement, along with merit, but the foremost focus should be on contributing to the forum, even if you do participate in campaigns.

Crappy constant posting can get you reported and could even lead to banning your account.