DD1 has 2 pinafores and a skirt, I change them when they are dirty or on Wednesday, depending on which comes first. Ditto cardigan. Polo shirts do 2 days unless dirty (though are changed more often in summer when she is a sweaty little mary). All clean undies every day.
But then, I do not change my clothes every day either, nor does DH. I think we can get a bit obsessed with having everything clean. If I've worn a top to work where I sit at a desk all day, managed not to spill anything on myself, managed to prevent the DDs spilling anything on me and it's not been a hot day, I do not see the need to wash the top. I'll air it and wear it for a second day before putting it in the wash.
[mucky slattern emoticon]