How often do you wash your bed sheets?
I only have a bottom sheet, disliking topsheets with a passion. During the summer months, I use a lightweight comforter rather than a proper blanket. Just one sheet, and one light comforter. During the winter months, I'll add a light blanket to the comforter for layered cold protection. I almost always have a fan blowing on 'low' in the bedroom when I sleep, partly for the 'white noise' it provides, and I often have difficulty sleeping well in a room with static airflow.
To answer your specific question, I don't wash my one bedsheet as often as I should, maybe every third week. I may plan to do it every ten days or so, but as with haircuts, I first must notice the need for such maintenance, then, after a proper procrastination period, usually at least a week to ten days, I will jump into action and do what must be done.