Use of light is one of my favorite topics and despite the frequency of darkness and low light environments daily, it seems to be misunderstood by most.
There are three reasons to turn on your light and use various techniques (bouncing/umbrella/etc) as needed in the left picture- ID potential threats, clearing unknown areas, and navigation (avoiding obstructions, furniture, legos). One burst of light resolves 2 of the three reasons and as soon as an unknown presents itself you can activate your light to ID/clear them. One burst of light as shown on the right provides all the needed info until we reach our next problem to solve.
Running around with lights on is unnecessary and provides too much info to people who are not working with you. Excessive light use shows your movement patterns, techniques, and allows others to track your location. As you can see from the picture on the right, there are no obstructions or unknowns until the first doorway, so it is safe to move in darkness to that next problem. If something suddenly changes, activate your light to resolve the issue for the needed duration.
There is also the option of flipping a switch on the wall which can be a good tactic. I personally prefer to control the light to my advantage.
Be aware, weaponlight and handheld light usage can differ slightly. The user of a weaponlight needs to be always cognizant that there is a weapon muzzle attached to the light and an extra layer of control should be mentally applied.
Low output lights do not provide the same advantages or usefulness as a brighter options. A Tlr6 for example is about on par with a map light and has insufficient output or throw to use advanced techniques which are needed with use of a weaponlight. Bouncing light at the feet, ceiling, or wall nearby an unknown can’t be done at a reasonable distance with a weak output light effectively. Why do we want to do this? We want reaction distance and weak output does not help maintain better distances from unknowns. Pointing a weaponlight at an unknown is not a practice that should be considered – bouncing the light is far safer. Moving the light and barrel to center of mass as needed to apply deadly force is something everyone practices at some point (up drills anyone?).
Obviously an article or post is no replacement for actual training. People scoff at the idea of low light training but those same people seem to freeze up when an issue presents itself. Don’t believe me? Try low light force on force training and get back to me. I pretty much guarantee you will promptly throw away all those weak lights and buy the better options that same night.