Dd1 loves her pinafore, and despite having plenty of skirts/trousers (she probably has got enough uniform for a clean set every day), will only wear her pinafore. It is washed on a Wednesday, unless she gets it dirty before that. She wears her blouses twice, before she gets a new one, unless one gets stained on day one. Her cardigan is washed on a Wed, with her pinafore. She gets new undies and tights daily, obv.
All of her friends do this too. When one of her friends got chalk on her cardigan at a play date at my house, her mum said she would wipe it off with a babywipe, because there was NO WAY, she was washing uniform on a Thursday night, just for the sake of one day.
YANBU.