While this course can't guarantee greatest possible marks, it can definitely equip you with the knowledge and skills needed to excel in your exams. Ultimately, your performance depends on your preparation, exam skills like managing nerves, and how well you apply your knowledge during the test.
However, Dr. R.G. Singh's experience (17 years offline and 5 years on YouTube) is a strong indicator of the course's quality and focus. By taking this course, you'll gain a solid foundation in the subject matter, which will significantly improve your chances of success.