I buy CR 123s in bulk, and because I have a 2 1/2 y/o we have AAA and AA piled high. W have a pretty good rotation schedule on them too, I've only had 1 pack of AAs get to the bottom of the box, and come out of the package dead. Using a flashlight all day every day requires me to have lots of batteries around. I generally keep 50 or so CR123s in stock, I go through about 6 per month, and about 9 AAAs per month, but... If a flashlight were my only light source, that would go up exponentially, so I don't have enough for that.