Hmm; sorry to hear that. You may need to increase the default evapotranspiration for Las Vegas – maybe add 10-20%. You can investigate what’s going on by looking at the soil moisture chart. There’s lots of hidden rows so be sure to click the tiny grey sideways triangles. You should be seeing evapotranspiration values around or above 0.30". The root depths in advanced zone settings can always be reduced to help reduce watering time and increase frequency.
But if you’re tired of messing around with Flex, it’s totally fine to revert back to a watering schedule you’re used to. There’s still lots of functionality Rachio provides for fixed schedules, so you won’t be wasting the device at all.