+1 on going without a light, when there is enough starlight/moonlight
I was gifted a Streamlight Stylus. I think it takes 3, maybe 4, AAAA batteries: I haven't had to replace them, yet. I have a pack of four, for when they do die. That light is too bright to test for DUI horizontal gaze nystagmus, but great when you can't see the trail at your feet. I wrapped the barrel in plastic electrician's tape, as I was used to using a Streamlight Scorpion, which takes two 123A batteries and has a barrel that is rubbercoated--so that you could hold it between your teeth, to change a tire (cue Ralphie, from "A Chrismas Story", saying "Oh-F...", when he kicks the lugnuts out of the hubcap, into the snow...

Standardize as best you can, but remember: batteries of that size, really don't weigh that much: if you have to carry a couple of different sizes, so what? Is your life really worth the difference the between the weight of a couple of batteries?