To maximize reliability, WiZ schedules are stored directly in the memory of the lights. This means that once a light has received a schedule configuration, it will be able to run the schedules on time as long as it remains powered on, thanks to its internal clock. Even if your internet connection temporarily goes down.

The lights need to be online to receive their schedule configuration from the Cloud and to check the time. So if you add/edit/delete schedules while your lights do not have an internet connection, those changes will not be applied. They will come into effect as soon as the lights will be able to reach the Cloud and get the latest configuration.

If on a given day your light is not able to connect to the Cloud to check the sunrise/sunset time, your sunrise/sunset schedules will still run, using the last known time (for example from the day before).

If you power off your lights then power them back on while there is no connectivity, then they will not be able to check what time it is, and schedules may not run.