If you post 3 comments in a row, then you do get locked out of commenting again until someone else posts–it’s not even timer based. Others have complained about this.
It’s unclear if this can be overridden by an administrator. It’s moderating something that we never found useful to moderate on our board before, so it obviously doesn’t need to exist. But we don’t have an active administrator right now, unfortunately. So all our “punch up” fix requests have gone dormant. The list is still pretty large–Discourse comes, out of the box, with a bunch of stuff set that it really shouldn’t, at least, for existing communities who already have their own standards. (Not to mention some features that don’t fit any forum if you don’t want it to become an echo chamber)