I just saw an article suggesting you should 'never' wash your jeans in order to retain their shape. Not sure I like that idea!
I tend to wash my jeans after every wear. I'll occasionally wear them a 2nd time only if I have had a 'home day' or not gone anywhere where they might get germy/dirty.
DH wears his a few times before he washes them. A mate of his goes months without washing his, he just airs them out on the clothesline.
What's your jeans policy?