@mattebury - depending on how many days a week you can water I see that there are three options to setting up the Rachio.
Go with a fixed schedule for the allowed days and turn on all the weather intelligence and season adjustment factors. I went with this as currently I can only water on two days of the week (I’m trying to get that changed for intelligent controllers).
Go with a flex schedule, but only on the allowed days. If there are fewer than three days a week for allowed watering, the flex schedule may water every time it can so the allowed depletion won’t be exceeded before the next time it can water. I believe the watering each time will be variable, just enough to fill up the zone. However, this watering pattern may train the vegetation to have shallow roots as there would be frequent watering. (Which is not what one wants. One wants to train the vegetation to have deeper roots.)
Go with a flex schedule and say the heck with the allowed watering days (I’m not advocating breaking the law, but just listing options) and let the schedule water on any day.
As Rachio computes water needs it follows the age old computing rule - GIGO (Garbage In, Garbage Out). In irrigation terms - incorrect zone settings will result in over or under watered zones.
If one wants to really dial in a Rachio and squeeze every last drop of irrigation water, then I’d recommend doing a catch cup test for the entire system. A catch cup test should result in accurate precipitation rates, irrigation efficiency and square feet for each zone.
Additionally, depending on the water pressure actually present at the nozzles, different nozzles and/or pressure regulation may also reduce the amount of water needed for irrigation. (Cue @robertokc)
Here is a link on how changing each setting actually impact the schedule -> https://support.rachio.com/hc/en-us/articles/115010379087-How-do-I-edit-duration-and-frequency-on-Flexible-Daily-Schedules-
Let the community know if you have more questions and I’m sure folks with respond with comments. This is the best thing that I’ve seen about the Rachio product is the community that supports it - most of which are more irrigation savvy than I am.