Another thing to check if you have not done so already is coverage . . . making sure the dry areas are getting adequate coverage. After messing with my zone duration(s), I had to create a new schedule to fix that (unfortunately, no reset that I know of).
The following is a pretty detailed summary of how to increase/decrease the duration/frequency (probably besides using the “Adjust” feature that might still be in beta): How do I edit duration and frequency on Flexible Daily Schedules? (rachio.com).
Here is something another community member said about adjusting it without the “Adjust”: Best way to increase water into a zone? - Schedules & Zones / Flex Daily - Rachio Community