Michael Black wrote:

If you want to gamble that there never will be a fire, then don't buy
smoke detectors and don't buy batteries for them. But so long as
you don't want to take that risk, you install the detectors and
change the batteries regularly.



I think those that advocate changing twice a year are taking into account
some people buy batteries made in China and sold at the dollar store twelve
years after they were manufactured with sub-standard ingredients.

I further suspect that brand-name batteries bought at a high volume retailer
(Walmart, Home Depot, etc.) have a shelf-life of five years and in minimal
use in a smoke detector of almost that long.