I’ve got a strange mix of units I feel comfortable with. Miles, yards, feet and inches, but then I switch to millimeters, microns and nanometers because of a couple jobs which did a lot of small measurements in metric. A mil (0.001 inches) always means 25.4 microns to me. For radio bands I figure wavelengths in meters, but always think of those as “big yards” when doing anything practical with them. Fahrenheit is for temperatures, but in college I was almost as familiar with Kelvin temperatures.
But don’t you ever get confused whether “nm.” means “nanometre” or “nautical mile”?