I presume if you think eighths of an inch is good enough then you mostly work with large objects. Luckily outside of USA, Liberia, and Myanmar inch-based scales are rare nowadays, but I still come across specifications in small fractions of inches for such things as manufacturing tolerances, drill bits, coating thickness, cable diameters.

Informal measurement of humans and beer is a nice quirk of the UK system, but in my experience it's not commonplace to use imperial units for anything where accuracy is important (except maybe jewellers, and arguably road speeds/distances).

See also, the monstrosity that is AWG: https://en.wikipedia.org/wiki/American_wire_gauge