I do this and the main reason is that milk with the greatest number of days has also been on the shelf for the least amount of time and consequently has probabl

I do this and the main reason is that milk with the greatest number of days has also been on the shelf for the least amount of time and consequently has probably had fewer things happen to it - like the refrigerator door being left open and the milk being warmed (slightly). For other items I reach in and take items from behind the first row for similar reasons since the retailer may have put returned items (which might be slightly spoiled or damaged) up front. This is also the reason I never take the last item of anything. So there's more too it than simple expiration dates. Retailer subterfuge is also a factor.