Is it a law/regulation/code that all hotels have to triple sheet the beds? And, is it true that blankets only need to be washed every three months?

I tried to find the answer on the internet, but am not having any luck. I thought all hotels beds are supposed to have a bottom sheet then a top sheet, then the blanket/comforter and then a sheet over that? But, that was not the case in a hotel I stayed in recently. I thought this rule existed because they don’t have to wash blankets often, and for that matter how often do they have to wash the bedspreads when there is one?