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Bopping along editing a science fiction piece. Good, good. Lovely choice of the metric system. Then I read “the whole nine yards”, buildings are referred to in square footage, etc.
Know the measuring system you are using. While a rare holdout and phrase may occur, such as “stones” as a weight unit in the English “pound” system, these holdouts are rare for a reason. Especially thousands of years in the science-fiction future or in alternate universes of fantasy. Switching systems throws people out of the world you are creating.
Measuring systems are part of the worldbuilding. Don’t crumble the foundations before even starting.