It is not only important to have the knowledge and understanding of how to navigate the code, getting prepared for your exam may also be preparing yourself mentally. If you have taken an exam and didn't receive a passing score, what can you learn from this? Read about successful people such as Henry Ford, Thomas Edison, or Nikola Tesla. They didn't give up, they would figure out "what can I learn about this" or "what can I do differently". If something isn't working for you then, change your approach!