The cloud enforces the limit.
As long as you publish only once per second, you can publish once per second forever. This is the recommended mode of operation.
However, in limited situations, you can send out more than that. The maximum publish size is 622 characters. Say your application generates 2K of JSON data, but you only want to send it to the cloud every 10 seconds. Since the data is too large to fit in a single publish, you split it into 4 separate publishes. Since that will still fit in the burst rate, you can send them out sequentially, without waiting.
You can’t do that continuously, so you can’t send 5 publishes at once. And you need to wait the recovery period (4 seconds) before you publish again after a burst of publishes.
But in this application, since there are only 4 publishes, 10 seconds apart, you can burst out all 4 publishes quickly, and not have to wait 1 second between each publish, because there is enough time to recover from that.