I just wrote this article and had an idea: https://community.rachio.com/t/accurately-configuring-rachio-advanced-settings-and-estimating-gallons-used/20252
What if you asked people (as an optional step) to enter in their water meter reading before and after each zone test during setup? You could tell the user that if they do this additional step, Rachio could more accurately estimate water usage in gallons.
You could provide some instructions on how to read your water meter with common examples (pictures), tell people to make sure they aren’t using any water in the house when running their test, and then run the test for 5-10 minutes and have the user enter in the starting/ending number from their meter. Then if my formula in my article is right (I hope it is, if not please correct me), then you could calculate the area setting automatically using the estimated nozzle rate of the head type selected. I think the test needs to run at least 5 minutes so enough of water goes through the zone to get an accurate reading from the meter.
By doing this, you can more accurately calculate area. Then you could display both time and estimated gallons usage on the home page, instead of just one or the other.
A catch cup wizard to guide the user through doing a catch cup test would be awesome. If you could build my article into a catch cup wizard, you could easily ask user for water meter readings there, too. All you need to do is run through the zones, have the user enter the catch cup data (ml and throat area of catch cup) and then you can accurately calculate efficiency, nozzle inches/hour, and area for each zone.
Finally, if the user manually changes the nozzle rate or area, they should be warned to do a catch cup test or the system could recalculate area based upon the adjusted nozzle rate and the original water meter usage readings during setup to recalculate area so estimated gallons is accurate.
Honestly, now that I think about it, by just having the initial water meter start and end readings from the initial test, assuming the zone doesn’t change, you could hide area from the user completely. It’s really irrelevant - you just need one accurate water meter reading running a zone for a fixed period of time to know how much water a zone uses every minute to estimate water usage.