More to the point what's the use of a RPS? When the area is too big.
It was in common use many years ago so a crew could take off, fly in radio silence and still have a reasonably accurate (i.e. safe) altimeter setting to use en route. That is why you can get the hourly plus the next hour.
It's less of an issue now that radio comms are so much better and ATIS stations more widely available.