The flex calendar view is a forecast, and not necessarily an exact representation of the scheduling. We take real time weather data right up until the schedule is going to run and make the decision about an hour before. Also, zones in a flex schedule will run independently since they might be tracking to different moisture levels.
We are releasiing simpler scheduling that is the best of fixed and flex schedules. The app has been submitted to the Apple store for approval, so we should be live very soon. Hope this helps.