I know - that's the way it is here too.
every other week when the cleaning people come. best 2 days of the month!
Every week. sheets, pillow cases and duvet. I can't stand dirty sheets touching my skin. TMI but I love having sex and sheets get messy. I have 2 sets so I do not have to do laundry every week.
Every 7-10 days. Pillow cases every 3-4 days.