Well shirts i can get 2 days out of, and if i dont know how long since it's been washed its the sniff test, jeans get washed if they are dirty iff not a good week or two again if i don't know how long its the sniff test, undis and socs get washed after one use, but if if i find them on the floor and don't know if they are cleen it's the sniff test.
"I wear jeans to work and I'll generally wear the same pair for the whole week and wash them on the weekend"
thats the same for my work pants (I work in an office)