I'd second the point on different cultures doing it differently. One of my profs once said he had a book written by two mathematicians, one German and another

I'd second the point on different cultures doing it differently. One of my profs once said he had a book written by two mathematicians, one German and another Italian. It was fairly evident who had worked on which part. He also mentioned that the "old style" German books would almost apologize if they "had" to use just a few pictures to illustrate something.