Where are you located? Climate matters, though ventilation is just as important in a cold climate as in a warm one because while chickens tolerate cold DRY air very well (they're wearing built-in down parkas), cold WET air is a recipe for frostbite.
As long as your ventilation is above the birds heads while they're sitting on the roost you won't need to close vents at all -- except perhaps for sideways rain that's defeating your roof overhangs/awnings.
My Little Monitor Coop came through Hurricane Florence bone-dry.
https://www.backyardchickens.com/articles/the-little-monitor-coop.76275/