How many pillows do you use when you sleep on the bed? Without doubt, I would say, "One." But this is not always an obvious answer in all the countries.
I was talking to my British friend and, for some reason, we started to talk about pillows. Then she said there was only one pillow at the hotel in Nara where she stayed. I didn't see any problems with that, but she said usually people need two pillows in the Western countries. Ah, that's solved my long-time question: Why Canadian people put many pillows on a bed even though only one person is sleeping? It was eye-opening. I think I became even smarter. :) It's always very interesting to talk to foreigners. Next time, I will tell her how to take a bath in Japan in return.