Depending on where you do your course.
If you study fulltime there is no need as the instructors will try to clarify grey areas, however with distance learning as in my case some times you might need a different explanation for clarity, hence you might also want to read a similar more in depth publication. Also with your DL package you should be able to phone up and seek clarification. However, the brush-up courses will help greatly provided you did your homework.
Hope this helps and all the best with your studies.