So this is why I have so many flashlights and batteries! Got home about 7PM and the power was out in the whole neighborhood due to some thunderstorms. Started getting dark inside around 8PM since it was rainy and overcast. This is where Medium mode really comes into play. Low doesn't give enough light and High burns through your batteries too fast. Also if I'm going to burn through several lights, I'd rather use AA NiMH power instead of risking too much discharge on my li-ion lights. I also have a lot of NiMH's lying around charged up. Good regulation is key, so my Fenix L2D excels by running on 2 NiMH batteries and putting off good consistent light for several hours.
I still used some 18650 lights with XM-L's on Low. Had enough to have light in every room of the house and a couple of lights in some rooms. After it stopped raining, I turned most of the lights off and walked the dogs around the block with no streetlights, but two 18650 lights.
Then the stupid power came back on at about 11PM. Just as well since I could use the air conditioning and I didn't want stuff in the fridge to go bad.