Once a week. Every Sunday. I started hanging out at home on Sundays to watch football, and since I was in all day, I created a habit of doing all my laundry from the previous week on Sunday, starting with stripping the bedsheets. Do all the rest, and finish with a load of towels (because the towels take forever to dry).
I like routine. And being clean.
ETA: Not that I’m a nasty dirty person. I do sweat a lot, but I keep the AC cranked and have two fans. But I totally agree with the mite dust and body flakes. Aaagh.