I am currently eating “prepper food” from my test shelf. It’s two cans of ready-to-eat soup. Both expired exactly five years ago. Both taste good.
This seems like the time for me to regain that storage space and restock it with fresh cans, but I’ve answered my question on keeping cans beyond expiration. Other than the test shelf, I rotate my storage, so I don’t need to know if food is okay more than 5 years after expiration. Acidic foods (usually tomato-based) can eat through the can and are very obviously bad around 2-3 years beyond expiration. Canned tuna can also be risky after a few years and is very obviously (open it outside!) bad. Otherwise, shelf life for modern canned foods is very long.
Generic recipe: One can of ready-to-eat soup plus one pound of pasta or rice. It’s not gourmet, but it’s adequate and allows for a lot of cheap and easy variety calories. I have better in storage, of course, but I can eat for $2 a day on that recipe.
I too, have eaten "expired date " soups and other canned goods; rotating canned foods should make such an experiment less likely, or necessary.
I do limit my food storage canned goods to the fully canned goods for storage; most 'store brand' goods are retort fully canned goods.
On the other hand, there are the convenience "E Z Open" canned goods, with the pull tab on top
and those I limit to two to three years past expiration, no longer than that.
After three years, the only thing protecting your canned goods is a thin layer of die pressed metal,
and a thin membrane of plastic can inner coating, protecting your food from botulism.
Botulism is a spore producing bacteria that is difficult to detect, even in clinical laboratories, and requires several days of testing.
If botulism is suspected, after the fact, treatment is to induce vomiting and bowel movements to clear out the digestive tract.
Discard any dented or bulged canned goods from your long term food storage; and yes, canned goods with high acidity need additional caution and rotation.
Good suggestion about extending canned goods with pasta; now if only someone would invent long term storage canned cheese (!).