Ask HN: How does the HN comment rate limiting work?

I took a several month break from HN and decided to have a go at participating again.

I now remember one of the main reasons I stopped posting: It seems that if I comment on more than a handful of articles, I am hit with a rate limiting message saying I am posting too fast. I guess I can see the reasoning behind that, but even after waiting several hours I still get the message.

Is this unique to my account or did the rules change earlier this year? It's nearly impossible to participate in productive discussion if you are limited to 5 messages per day.