I have flown dozens of private jet flights ( wealthy friend) and I never close my window shade. That said others passengers have and it is almost always because they are napping or reading. My guess is business execs are so busy, that unless they are working they use a flight like this to catch up on sleep.....and even if they are working sometimes the glare of the sun is too much coming in the cabin. Unlike myself who feels like a kid in a candy store every time I fly private.....they are so use to it....it has more to do with creating the right ambiance and less about the luxury.