We occasionally get engineering diagrams from clients in the US and they're always going on about screws that are 2/3 of an inch long. It's not just that you're not using metric you're using a weird fraction and not a decimal.

It's super confusing when you get into high precision stuff because then they start going on about 128th of an inch. Just tell me how big you want it, stop telling me what fraction of a different measurement it is. Surely there is something below inch that you could use. I still wouldn't know what you were talking about, but at least it would look less stupid when you wrote it down.