I know there are many threads about this already. I will add one more and hope rachio can see the demand for it.
Even with all the intelligence, I find that rachio over waters. I played around with it a LOT last year but at the later months of the season just started using the app to water manually.
It would really help to throw a few $49 sensors 
in the ground so rachio can accurately know what the moisture level is in the ground. I would easily save the money for the sensors in just one season of water savings.
I understand there are a couple of options to hook up third-party sensors to the rachio controller rain sensor port but those system usually come with only one sensor, multiple-sensor system is too expensive, come with an additional controller and will put the full system on standby instead of the zones where the sensor is installed. Not ideal and just bulky.
These sensors can’t be that hard to make and will generate another revenue stream.