I notice that some of the disposable butane lighters I have have a lower level progressively about every 6 months or so. I've never had one run out before I got rid of it, but I have seen some lose half their fuel load in the course of a couple years.

For an EDC, that is nothing, but for a backup, it is a factor to consider. Matches don't last forever either I reckon.
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The ultimate result of shielding men from the effects of folly is to fill the world with fools.
-- Herbert Spencer, English Philosopher (1820-1903)