My brother still dumps milk on day of purchase, I only dump it once it forms little lumps in coffee, well actually it goes into the porridge.
He also used to chuck out all the surplus food if he had hosted Xmas day, except everyone else used to take it home, so if he hosted you'd only need to buy food up to Xmas eve and maybe for NYD as there was that much left over, oh and that's 3 families tidying up.