The Surefire company of Fountain Valley, CA is the industry leader for flashlights for military and law enforcement. These applications require dependable lighting. I note they tend to lean toward the ultra reliable CR123 3 volt Lithium batteries, variable intensity dimmer switches, coupled with LED bulbs, which make for a combination of light adjustable management and long life usage, both in terms of bulb life and battery life. Additionally the power curve of the Lithium battery differs from the carbon or alkaline battery in that it stays consistent right up to the dead end of the curve, then immediately drops off. Carbon and alkaline batteries tend to have a power curve similar to one half of a strung longbow. The Lithium batteries also have a 10 year shelf life, far superior to the carbon and alkaline versions.
When I'm in the woods hunting I typically start out in the dark and end my day in the dark, thus my head lamp gets used twice per hunt day. For general walking in the woods very dim light is all that is necessary. Just a few lumens is all that is needed for locating where to place a foothold. I tend to use a red filter to preserve night vision as well. The red filter also preserves a hunter's steathiness on approach to the final hunt location, masking the hunter's signature on approach in the woods from game.
This is where the Surefire Minimus Headlamp really shines (pun intended). The Minimus Headlamp is dimmer switch adjustable in intensity from zero to 300 lumens (far too much light needed for the return to camp walk). There are also battery compartments that would mount to the rear of the head strap which incorporate (3) of the CR123 batteries which extend the run time to as much as 144 hours. These same battery compartments are set up such that you could swap out the CR123 batteries for standard AA sized batteries. Real versatile Professional units.
The Surefire Minumus Headlamp has been a foundational part of my hunt kit for many years. Has never left me in the dark. Some will balk at the price of the Surefire.....but in any industry there is the industry leader standard and the imitators that operate in the wake of the research and development investment performed by the leader....