Very instructive! I might have a useful addition to this video.

In one shot there is a Maglite standing on its head, and you tilt that a bit to see if it the led is functioning.
Of course you have to do that, because you have a wooden workbench that absorbs the lumens.

BTW, that’s why I prefer lights with a (slight) crenulated bezel.
If that’s not the case, I use an opaque polyethylene cutting board. Where I can see the light shine “through”.
You don’t need the full 8”x 10”, just a piece big enough for your largest bezel to rest on.