Flexible daily will record precipitation and add it to your zone soil moisture level, (+credit).
If this is enough to offset the evapotranspiration (ET), or -debit, the day it is supposed to run then we push off watering till the next day.
Also, if the forecasted precipitation is enough to offset ET (debit) than we push off watering.
This can all be tracked in the zone soil moisture graphs.
More information on the flexible daily:
You can always set a manual rain delay if you want to pause flex scheduling for an amount of time.