I ran across a well sealed (so I thought) packet of matches that I had prepared about twenty years ago. Stored for a while in a hiking staff, the capsule had been sitting out in an occasionally wet environment - a very leaky shed.

I opened the capsule and tried the matches. Bleached white, they didn't even give a hint of sparking, although I had included the abrasive strip from the original match box in the capsule .Also a total failure was a match with a lacquered head.

Maybe it is worthwhile to check more frequently than every twenty years or so....And while you are at it, check the edibility of whatever food you might have stashed....