Drywall photos & tests are for comparing different flashlights. One can see that flashlight X has a small, high intensity (far reaching) hot spot, flashlight Y has a wide, low intensity flood kind of light and so on. The trained eye can see these things easily.


Apart from providing the "flashlight experts" with a neutral frame of reference to help evaluate the flashlight, drywall photos have zero to none practical applications. Unless you know what to look for in a drywall photo it will tell you zip and nada about how the light perform. Use and abuse it, that's the only way to see if it works for you.


A special branch is called "drywall hunting". It is not the drywall that is hunted (for that a hammer is recommended), rather the drywall is used to hunt for imperfections and flaws in the beam. Slight imperfections in the beam have absolutely no practical consequences, but flashaholic hut for them all the same. A rather nerdy hobby... (Beams bad enough to have practical limitations is a thing of the past, or of very cheap low quality flashlights).