Each and every time this comes up. I say that I am familiar with the metric system and use it for quite a few things, but I specifically prefer woodworking in fractional inches because working in base 12 and power-of-two fractions is closer to the tasks I need to perform in the wood shop than base ten decimal math does.

I give real-world examples like “divide 19mm, a commonly used stock thickness, by three to make a tenon, you get something point 3333 repeating of course” and they 1. downvote and 2. Invent sizes that we don’t conventionally mill stock to thinking they found a “gotcha.” “Well what’s 2 inches divided by three?” we don’t mill stock to 2 inches thick, we’d use 1 1/2", a third of which is 1/2". Y’all actually do use 19mm.

But Americans use inch fractions so inch fractions must be dumb and bad, right?