[jodi]

Umm...when they smell. For everything!

Seriously, clothes are worn until they are dirty - usually at least twice, sometimes 3-4 times for items like work pants (I work at a desk). Undergarments - always one wear only, except an occasional pair of socks that I might wear for an hour or two before bed.
Sheets - no time schedule. I guess I get around to it when I feel like it, or when something happens, like the cat making a mess (let's just say she has a delicate stomach). Sorry if TMI! We have a duvet cover on our down comforter and that gets washed about once per month (or more, depending on aforementioned cat).
Towels - I can use for a week or more. When they start to smell mildewy, they get washed. We only have two colors - blue for me and white for DH - so there's never any confusion about whose is whose (which used to happen to our family when I was growing up because my parents would always make us use the towel more than once, but you could never remember which one was yours).
Kitchen towels and dishclothes are used for a day or two, then thrown in the laundry with whatever else we are washing, unless they are paticularly dirty - then we save them for a bleach load. I also use baby washclothes for my kids rather than paper towels. They are one use only, then thrown directly in the washer for whatever load is done next.
We have two dogs, but they are not allowed on the furniture. We shampoo the carpets about every 3-4 months.