Emil, sorry for the delay. Yes I did see your response and will include responses to your questions below. I should have mentioned that all I was doing at the time was turning season shift on for the fixed schedules that I had used last year.
To answer your questions:
@davelr, sounds like you're applying custom durations to your zones? Rachio will recommend a duration based on the zone settings selected; curious if you're overriding these values?
No, hadn't altered anything. These were fixed schedules and I just input a starting time of 9 min. for April. I assume now that the season shift won't really work correctly for a fixed schedule.
I'm not sure if you've reviewed this support article yet, but it details the math behind how the curve is calculated and applied. My assumption without looking at the data is that your base duration (9 minutes) is the root cause for the 15 minute max duration.
I had assumed that for a fixed schedule if I input a starting duration for April then the May duration would be adjusted by the curve, and so forth, whether or not this is the correct thing to do for the root depth. Obviously this isn't what happens which is why I concluded that the season shift isn't applicable for a fixed schedule. If I'm correct in that conclusion, I'd suggest altering the programs to not allow season shift to be applied to a fixed schedule to avoid confusion.
Remember to factor the intervals of the watering into your math. Your controller is currently on Standby so I cannot review the schedules, but happy to check the intervals if you're okay with me taking the controller off Standby.
Given the above, I conclude here that the only way to properly apply an increased watering requirement curve to a fixed schedule would be to do it manually.
You're certainly welcome to take the controller off of standby if you wish, I currently have the water valve closed, so no harm. However, I've deleted all of the fixed schedules from last year and turned on monthly flex schedules to see how they would work. This does result in situations where the weekly frequency of watering days exceeds those specified by Denver Water. I'm going to check with them to see if they have a problem with this or if they have some type of waiver for smart controllers. I know they have a rebate program for smart controllers, so this may be possible.