An 18350 cell will, last about 2-3 hours depending on brightness and the driver you have, obviously a boost driver would last alot longer but with lower max output.

I would agree small cell size makes it less appealing to carry on a long night walking etc but I guess that comes down to knowing your situation. If I plan to be out for a long time I’m grabbing a D4SV2 or DM1.12 with 26800 tube or a dual 26650 light like the L6 or sp70