Lithium primary cells (CR123, etc) have a shelf life measured in *decades* (usually about 20 years to 75% charge or so).

My car's glove compartment has a single-cell CR123 light as "lifeboat" gear - i.e., it should work as intended even without regular inspection & refurbishment / replacement.

There are more in the house, one on the ledge behind each toilet. When I lose power the bathrooms are the darkest areas in the house, so odd as it sounds it makes sense there.

The latest generation of Eneloop cells - not yet available in the US - are rated to retain 70% charge after 5 years. That's "lifeboat" territory, and Eneloop doesn't have all the safety and hazard issues even small Lithium cells have.

If you live in an area that sees extreme temperatures it's worth testing at those extremes. Many fully-charged batteries becomes useless below 0F.