As I noted in the blog post, the storage resides within the cluster. It is storing small values (log sequence numbers) so the space is used with great efficienc

As I noted in the blog post, the storage resides within the cluster. It is storing small values (log sequence numbers) so the space is used with great efficiency, but there is a finite limit. While I don't know the specifics, I would expect that the mapping (time to size) was chosen based on real-world historical data. Cause that's how we roll!