I really want to use the Flex Schedule feature, but at present, it's 'start point' is really inflexible. I may just not be using it correctly, but it seems like you have to correctly input your sprinkler capacity, square footage and vegetation types to get it to start correct. I'm sure I have the right soil types (soil test) and vegetation, but had to guess on the other points, which of course isn't enough for the feature to work correctly.
My suggestions are:
1) You also allow Iro users to start a flex schedule by giving the system a 'known OK' schedule, and have it work from there. I obviously used wrong parameters -- got watering times 3 or 4 times longer than what I know works well in my yard. Or... work from your 'fixed' schedule to 'flexify'.
2) And, query the Iro user to from time to time check the top X inches of soil moisture and also glance at vegetation for obvious water stress (harder for the untrained). Both of these could create an interactive process where it gets non-sensor hints as to too much/too little water. Could also just sell people a moisture detector to do hand readings for this, though this is more intrusive of course than someone checking by hand and just doing the 'how deep did you have to go until you 'felt' moisture? test.
I currently do something a lot like flex by hand and have a lot of non-standard zones (a 1 hour drench/drip zone for trees that runs every 10 days in summer, every 14 in fall/spring, and every 21 in winter -- though would love Iro to better optimize than that for me).