Months ago, actmyname tested his posting speed when Yobit spam popped up. He made his posts at the rate around 58 posts/ hour (I remembered 5x posts/hours) with post quality is much higher than spam posts from shit posters.
Here you go:
I doubt that if someone can make such posts, there is no reasons to judge them break forum rules.
Personally, if I compose my posts (with good quallity) for different topics, then post all of them at once; I don't see anything wrong and troubles with forum rules.
Nevertheless, in reality, no one has such posting skills. We (non-shitposters) usually spend our time for only one or two posts in different topics. We need time to read, search, compose, and answer with posts, and sure we can not do it at the same time over many topics.