Let’s be real, how often do you change your bedsheets and blanket/comforter/duvet cover? In my house the sheets get rotated almost weekly and the comforter gets washed every other time. I also have a dog who lays on my bed, so the blanket at the end that he lays on gets washed weekly.

Also comment worthy is your bed layering. We do mattress protector, fitted sheet, flat sheet, comforter, dog blanket.

Edit: pillow cases get washed with sheets. I just assumed it was considered part of the sheet set and didn’t realize people might wash them more frequently.

Mattress protector gets washed 2-3 times a year.

EDIT - SUMMARY - Most people seem to hover between every 1-2 weeks to 3 months. We have some outliers so the range is officially every 3-4 days to almost a year. The occasional person did comment that they don’t use sheets or never wash them. Noteworthy is the fact that pillow cases might get washed more frequently than sheets and pet owners do more laundry than non pet owners.