Part of the problem of mixed system is lack of intuitions. I grew up in the metric system, so I still struggle with intuitions from imperial systems. (It's very

Part of the problem of mixed system is lack of intuitions. I grew up in the metric system, so I still struggle with intuitions from imperial systems. (It's very hard for me to "feel" 10 feet, while I have an instant feel what 3 meters is like.) Most cases, this won't cause issued beyond missed perceptions, but it can hamper the ability to detect anomalies -- perhaps part of the reason what caused some of the incidents described in the article as well. Long ago, I once overheard someone's conversation, this was an architect in the process of designing a home for foreign market, and he was designing closets in some room too small, again, because he had to work with obscure units (for Japan, they use "Tsubo," about 3.306 square meters / 35.58 square feet -- and yeah, this is one of the few places that Japanese people are still stuck with customary units...)