Focus light necessary for macro?

Like Tim said, other than dawn, dusk and night dives, I never needed a focus light with D500 and 60mm macro, but with 105mm on the D500 or Z8, a focus light is useful far more often, as I recently found out. There is a wide range of sizes, features and power available and ulcs has some lightweight mounts that fit almost anything.

Not what I use, but I just threw this 120g thing together together to illustrate how small one can go:

Orcatorch D560 700 lumen 3.5" light with 14500 battery on a ULCS ball mount.

To paraphrase a credit card commercial, What's in your housing cold shoe?