I spoke with a stutend yesterday that said what he does, is take the practice tests over and over until he scores a 90 or better. Sometimes if he is feeling unsure he will take it until he gets a 100%. We use several pools of questions so you won't get all of the same questions every time you take a quiz. Good luck.
Hi Charles, To add to what John said, make sure you are very comfortable with each topic in the course. You will also need to look at the White Papers and FAQ for the various AWS services. Once you are comfortable, then take the practice exam. If your score is too low, go back and review that topic again. Every person is different. One person who takes the test in two weeks but spends 12 hours a day studying and another may take four months studying two hours a day. I wouldn't worry so much about comparing your study time to others. I would focus on making sure you have the right study plan based on how much time you have available. Check out the course scheduler feature. It will help you to see how long it will take to get through the course based on your availability.