I went 3 weeks in September on the John Muir Trail using a Thrunite Ti-3 (AAA) with a single lithium primary. Never used the highest mode, just firefly or the 10 lumen low. Still had juice left after the trip, just a single AAA battery. If you are not hiking at night, you really don’t need much light in the outdoors. I guess if you are in the middle of lots of trees that could be different, but the canopy in the high Sierra is not very thick.