The amount of time it took to study a book in college depended on many factors, such as the subject, the method of self-study, and the efficiency. Generally speaking, if it was a relatively easy subject such as literature, history, etc., self-study may take a few months, and for more professional subjects such as mathematics, physics, etc., it may take a longer time or even a few years. At the same time, the efficiency of self-study is also very important. If you can adopt effective learning methods and techniques, you can master knowledge faster. Therefore, the time for self-study varies from person to person and needs to be determined according to the individual's situation.