I like the fact that pretty much any appliance these days is covered by either AA or AAA batteries. Head torches, portable flashlights, testers, meters and lasers and all sorts...still a few needing a PP3 though.
Plus, some stuff has button cell backup cells onboard, but they don't need replacement very frequently.
What i find tricky, because I am old and decrepit, is that the light from LED torches seems to be still bright and white even when the batteries are nearly done...so, you switch it on, it looks ok at first glance, but when you go to use it, it is poor at illuminating. I suppose that's because of the nature of LED...it looks fine when you look at the lens, but when you try to use it, it fails to light up the workspace as you expected. Guess it's a throwback to the old days when batteries faded and the light got yellow and dim.
Sorry, showing my age here! That's why I said in an earlier post, keep plenty on hand, and change them often. Frankly, I don't know how I survived without LED head-torches before...you simply can't have enough of them! Car, toolbag, house...at least 2 in each location...and camping, walking, cycling...and they are so inexpensive nowadays...a triumph of modern technology in my opinion.