I do laundry about every 2 weeks. Usually when I run out of shirts, boxers, socks, or pants. I use fresh undies and socks every day, but I own more of them than shirts or pants. They all tend to run out about the same time. I own a washer and dryer. Laundry is typically:
Empty few clean items out of laundry hamper (because I don't put cloths away, just live out of my hamper)
dirty cloths -> hamper -> washer
Everything goes in 1 load along with as many towels around the house fit in to top it off. Cold wash cold rinse. Then dry it.
If I can't wash it in cold water with everything else I own then I don't need to be wearing it.