Do you have a 'white paper' on how the daily 'after the fact' Crop Evapotranspiration numbers (CE) are calculated?
I think what I'm hearing, first from McKynzee, and now you, is that for identical cloud conditions (and maybe wind conditions), for say a day in July versus a day in Jan., the 'after the fact' CE number will be identical (no variation as a function of temperature or time of year (growing versus non-growing season)).
My conclusion is simply that the Rachio product is not as aggressive toward limiting water as I thought it was. And that making change to the CE number in spite of identical cloud cover days in Summer versus Winter, and in 95 degree F versus 40 degree temperature, is opportunity for enhancement.
And thus the Rachio product is basically a 'follow the rain' product with a fancy front end that results in per-zone duration values that we all used to simply set via guessing at 'number of minutes to run' on our old controllers.
I used to use a Rain Dial RD1200-R controller coupled to an Irritrol Climate Logic unit. This system was more crude in many respects compared to replacing it with Rachio product, using an onsite measurement unit for ambient temperature, rain and cloudiness detection (solar insolation sensor) versus now being connected to a nearby weather station. The Climate Logic unit included a flash card of seasonal weather change patterns for all over the U.S., and by specifying your ZIP, you got benefit of reduced watering in the wintertime and with cold temperature.
Rain Dial's accomplishing with hardware what Rachio product wants to accomplish with s/w (keeping track of the soil's current moisture balance to determine when to irrigate, and on a zone by zone basis). It's increasingly clear now that the Rachio product isn't (yet) where competing, h/w based products have been.
I look forward to seeing what Rachio's continued product development brings to the table.