I've kept ketchup/mustard and relish up at the cottage, year after year and never in the fridge. Relish would get used up for some reason but mustard/ketchup would last 3 years or more. Was fine! All of these sort of products are preserved with vinegars, sugars - they are not going to go bad easily.
Powdered stuff like Bisquick would get mealy worms or moths or whatever they're called.
My son once looked at the date on a box of KD at the cottage one year and said, and I quote... "MOM!!" lol the foil pack of cheese was rock solid - but the pasta was fine...
(think it was 4/5 years old - common! it was at the back of the cupboard!)
I have individual packs of yogurt in my fridge that are several months old past due. Had one yesterday... it's was fine!
Packaged foods now-a-days are so processed, they usually only go bad if you use dirty utensils in and cross contaminate. Not even mayonnaise goes bad anymore (***please note.. other
than homemade ones with egg***) They are so processed, pasteurized, homogenized... they ain't gonna go bad sitting out a bit. I put most things with mayo on ice only because I like them chilled not out of fear of bacterial growth.
Like was said earlier, common sense, common sense, common sense.