> Most people shut them all off as soon as they sit down.
Why do they do that? I leave mine of full blast the whole flight to stay cool.
Personally I've always found the constant airflow starts to dry out my eyes, making it very uncomfortable
Ah I just close my eyes and go to sleep on flights.
Those are in addition to the main AC.
Those don't matter for the ventilation, they are just additional small nozzles to the main one hidden behind the panels. Shutting them or not doesn't affect the quantity of air delivered to the zone.