Professional instruction is important for several reasons. First, a professional driving instructor is more familiar with the rules of the road than the common driver, which means you are more likely to learn from these professionals the proper habits for driving safely, confidently, and correctly in all driving situations.
This is also a reason why we often suggest against parents being the first driving teachers of their teens – sometimes more experienced drivers, as parents usually are, will accidentally pass on driving lessons that are too advanced for their teenagers. Experienced drivers often use “shortcuts” in their driving, such as reversing quickly, parking in narrow and unusual spaces, completing a u-turn in a busy area, and going past the speed limit on open roads, which inexperienced and new drivers should not be exposed to until they know how to drive traditionally and correctly. Perhaps more importantly, many of the shortcuts used by experienced drivers would cause a point deduction during a road test!
Second, professional driving instructors are familiar with the actual road test location, which means you will be able to practice driving on the actual test route. This helps new drivers become more comfortable with the actual road test before it is administered.