Learn four high school math books a day. That depends on what you used to be. If you have been exposed to it before, it is not studying but reviewing.

If you haven't touched these four high school math books before. After all, it is difficult for you to learn four high school math books.

Please put it another way. Have you finished learning or watching? These are two different concepts. If you learn to use it, to what extent have you learned? If so, what is it? Do you read quickly or with relish?