One of the most challenging things about college is time management. It’s not that you don’t have enough. In fact you usually have too much time, and as a result time gets wasted. If you take good notes in class, and spend one hour reviewing your notes every day before going to sleep, you make use of the power of the subconscious (下意识) to absorb information and by the time exams come around you’ll know all the material on a subconscious level , and you don’t have to sit up the night before exams. Considering the amount of free time you usually have in college, one hour a day is not much in view of the long-term benefits.