Up and down at various times, not just day versus night. Down for moments of privacy and to control direct sunlight. Down might mean the translucent "day" shades, or the opaque "night" shades. When I have no lights on inside, might use the "day" shades at night.
Up for letting light in, for ventilation, for looking outside. If I sleep with windows open, the shades on those windows will be up.