I seem to recall hitting the limit after posting something like two replies on one story and being confronted with “you’re posting too fast” when trying to post an unrelated comment on another story.

I think the limiter kicks in as soon as one of one’s comments get any downvotes at all (i.e. even when also being mostly upvoted), but I’m obviously not sure about this.

This is obviously very annoying, and I can’t see how it helps discussions.