Yichin. follow your coach he is correct in what he is telling you. And as he says don't depend on what the book says. I would do as he tells you and if you want confirmation go to Learn the Dances Waltz Spin Turn on this site. Use your space bar to get frame by frame. You will then see what your coach wishes you to do. Competitors do, do it. One more thing how big do you think a spin Turn should be. Taking a normal door as a measure. How many doors do you try to cover. A door is 32 inches or 81 centimetres wide. See what your coach says. Good luck