It's just a suggestion for us. If it's milk, I usually smell it. If it doesn't have a sour smell I will use it after the expired date.......same with sour cream. Dry goods, can goods depends on how long after the expired date. We are usually pretty good about using things up before they expire.
Just a suggestion for us....except the milk and medication. I'm not a fan of milk anyways (alone), so when the date approaches, it's out! Same with medications too.