@motero8111 Rachio will calculate the duration for you, but it needs to be told more about your local soil, vegetation and irrigation hardware.
Be sure to take a look at the Web Soil Survey website, and find your soil type and the associated ‘Available Water (AW) value’. This is very important for your scheduling. Set your Area of Interest (AOI) from the map, then use this post to find your soil type and associated AW number. Once you have the soil type and AW number, set both of them correctly in the zone setup.
Choosing 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.
I found it easier to just order these, and use their online calculator.
Bermuda roots can very 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. Given what you’re saying about previous neglect, I would start at 4" and work your way up over time to whatever is reasonable for your soil. Deeper roots will mean a heartier lawn with less water used.
Once you have the 3 areas dialed in report back and I’m sure others with similar setups can give you an idea if the watering schedule seems reasonable.