That’s what I was referring to, yes. I heard of a situation during a merger where the Japanese delegation took turns sleeping, while the other delegation was up all day. As a consequence, the Japanese delegation got their way because they had more stamina.

Sleeping at work is sometimes allowed because it's accepted there is such a chronic lack of sleep generally. If they were taking turns sleeping it means they probably already were overworked and needed a nap. The story sounds like "history is written by the victors" or just more fetishing of Japan.

No this is different. Lot of Taiwanese companies have the after-lunch rest (source: Taiwanese friends). I never heard as such for Japanese companies.

I've had many years where a short nap after lunch dramatically increases my productivity.