You can watch during specific times. On average, drones fly between apx. 2 to 6 PM, but this is largely weather dependant.They have a schedule. You probably caught them when they were on their way out to the DCA (Drone Congregation Area).
Not every afternoon. Drone flying is weather dependant, and requires a temperature of about 63F or more to fly to a DCA. If the weather is bad, drones will make up for the lost time with increased flying time the next nice day.I didn't intend it as a joke. The drones go to the bee singles bar (AKA Drone Congregation Area or DCA) every afternoon and return every evening.