I wear stuff until it's either visibly dirty or it smells, for the most part. I wear fresh underwear every day, or twice a day sometimes even, but I do reuse wool socks. I knit them myself, and they're lanolized just like a diaper cover, and I can get a while out of of them before they have an odor and need washing.
DH wears his work clothes maybe twice at the most, because he's understandably worried about looking good at his job, but a lot of times with his casual clothes I have to say things like, "Uh, hon, that shirt could really stand a wash..."
DD, though, cannot get more than a day out of her clothes. She's 19 months and plays in the mud and in the sandbox and with water, and she's the sloppiest eater you'll ever see, and she's usually GRUBBY by the end of the day. And we rarely get through the night without a bit of wicking from her diaper, so even her pyjamas don't last more than a day.
I do 7 loads of laundry a week as it is, and that's ENOUGH for me. If I had to do more I'd SCREAM.