This post is NOT intended to replace any of the great resources available at support.rachio.com. In fact, I'm pointing to many of them here. However, when turning on Flex for the 1st time it can be tough to see where to start, and what some of the biggest factors are to getting a schedule that makes sense for your yard. Hopefully this helps a bit.
With these steps you'll be telling your Rachio software about local soil, your vegetation and your irrigation hardware.
SOIL (start here!)
Don't underestimate how important the soil setting is! Also don't just take somebody's word or your intuition for what type of soil you have. Unless you've had your soil tested,check out this guide on how to find the data you'll need, and where to put it into your Rachio settings.
Do a little bit of research based on the vegetation that you have and their maturity. Setting the right root depth for ALL of your zones is very important to getting reasonable Flex Daily schedules. For lawns there are 'soil probes' that can help you determine how deep your roots go. Otherwise, do some research, including asking on these forums about typical root depth settings.
Here's an example of information I've collected on Bermuda root depth:
Bermuda roots can vary quite a bit in length depending on the soil type. Harder clays will be in the 4-6" range, whereas in sandier soils they can get as deep to 8-10" if watered properly. Figure out your soil type first to see the range.
As you find information on root depth for other grasses, plants or trees reply to this post and share what you've learned!
IRRIGATION HARDWARE (Lawns):
Choose the right Nozzle / Precipitation Rate (PR)
OPTION A: Use a default nozzle type to set your PR:
OPTION B: To get a more accurate idea, you'll want to run a catch-cup test and create a custom nozzle instead of using the defaults. Doing this will also point out inefficiencies in your irrigation setup that are often easy to fix.
Rather than using cups I had lying around, I found it easier to just order these catch cups, and used the associated Orbit online calculator.
IRRIGATION HARDWARE (Drip emitters):
One of the most confusing aspects of setting up the drip system with Rachio is getting the correct precipitation rate (PR) for your zone. This calculator will help find the PR for 'single-point' emitter systems which are common in Arizona and some other parts of the country.
If you have continuous, evenly spaced emitters you can instead try to calculate PR using a water meter + calculator found here, or an online calculator like this one.