Memorising practice questions instead of learning the underlying concepts often leads to failing the theory test.

When you study for your theory test, it is easy to fall into a trap. You might just memorise the answers to practice questions. But the official test will not use those exact same words. They will ask about the same road rules in different ways. If you only memorize the answers, you will struggle when the questions change slightly. You need to understand the actual rules, not just remember the letters A, B, or C.