I use a 16 zone Gen 2 (with 13 zones being used) and have for a few years.
I live in Palm Beach County, Florida. We water here year round. I get reclaimed water, so never any water use restrictions, and the water is very cheap.
I tried Flex Daily and Flex Monthly. I really tried to make the scheduling systems work, and spent a lot of time to try and understand how they work, asked a lot of questions on this Community, but in the end found it too complicated, and I finally reached the limit of the amount of time I was willing to dedicate to this.
It has been over a year since I gave up, but I remember playing with the settings and watching the zones percentages of saturation, hoping it would water my grass while I watched it turn brown.
I have a Davis Vantage Due weather station, connected to PWS Weather (PWS_BOCA33432) with a Meteobridge, which is a considerable investment. So my Rachio has the advantage of knowing exactly the amount of rain I am getting, the temperature, wind speed, the humidity, etc., but I still could not figure out how to configure it to keep my grass green.
Unless you live somewhere where there is no rain, I think having your own weather station where you get the exact weather information probably goes at least half way to the goal of saving water and getting your yard the correct amount of water, even if you are on Fixed schedules.
So for now, my Rachio knows if it rained, the wind speed, and somehow it figures out if it is going to rain in the next 24 hours, usually correctly, all from my Davis weather station, and it usually does not run when not needed.
The other thing I have done is to install drip irrigation on everything that can be watered by a drip line, and kept my spray heads in good shape.
I notice that a lot of people that have replied to this post say they are engineers or worked in tech jobs for Sony or Silicon Valley, and even these engineers and technical folks think the system is too complicated. I agree if Rachio wants to be a successful mass market device, it needs to be able to attract people that are not technical and right now is way too complicated for the average consumer. Most people do not want to have to spend the time it would take to understand how to make this work. In my case, I gave it a lot of time, but in the end just reverted to an irrigation timer, but with the benefit of it knowing how much water I get at my exact location.
And I too offer this in the spirit of friendly advice. I want Rachio to be successful.
Thanks for considering my comments.
Eric