Whenever I buy new socks (Gold Toe for me), I always buy 42 identical pairs. That gives me six weeks of socks. They last at least 5 years. Then I replace them all at once.

I buy all identical socks each time, all the same style and color, so that I don’t have to waste time matching them. After I wash them (once every six weeks) I can just dump them all in a drawer. Done.