@thegrindstaffs, we do ask for your nozzle type but do not require pressure data.
We currently do this on all schedule types. The 2.5 version of the app will dynamically change your watering interval by month as well.
Just a heads up that Flex & Fixed schedules are getting hitched in 2.5! Very exciting scheduling enhancements that leverage the benefits of both scheduling models. To learn more, please see this thread.