as a mechanic working in a hodgepodge US/EU factory line, I have to suffer through always carrying double the tools to service metric and SAE machines. and after so many years in the industry, I still slip up and say 3/16 when I mean 3/8 sometimes, because fractions are a shit system for wrenches.

oh, and some of our linear encoders readout decimal-feet, because fuck it, why not?