Many students seek out practice questions as study aids. If used in the wrong way they can actually be harmful to your learning, your career, and chance of passing the exam.
Used in limited numbers and in a a thoughtful way practice questions can be an asset.
Practice questions can be an asset if you use them as mini research problems. Every service and requirement mentioned in the question can be researched, and every suggested solution can be researched. By researching around the topics and in context, you can more efficiently build your mental model and your ability to recall and apply those facts.
The risk of practice questions is that they can be a huge waste of valuable time.
Time spent rehearsing & memorizing random facts without understanding the context behind them is counter productive. I know some students want a hundred or more practice questions. This is really a waste of time as you will spend so much time practicing questions that you will be missing out the opportunity to actually learn. Also there is the problem that the questions and answers on many question site are just WRONG and the student ends up memorizing rubbish.
Remember that the objective is a productive career, with respect and a good income. A profitable career comes from demonstrating advanced understanding and insights (not memorization of random facts). How to achieve that is not always obvious to some students. That is why we produced the AWS Exam Prep Guide (also useful for other vendor exams).
Focus on the knowledge, understanding and insight that you can get by researching each question. Don't try to practice and memorize questions as a way to pass the exam.
See also the discussion about topics covered on the exam which will help you focus your study.