I believe that also Narbik WB would not help you too much to pass the exam . It only helps you to increase your knowledge.
Still the main part is experience and other managements area like time and stress and being self-esteem .
If you take V.5 as a real example and many one has had real-experience in both daily life and Lab exam, you could find out in less than 2 hours it's extremely difficult to solve the Tshoot questions which had not been seen before that time.
Here, the problem is much more than Narbik WB or any vendor's WB/Training here just your experience could help you to achieve ticket.
Many with possess exact scenario also had failed multiple timesđź”´, consequently, more than WB what is matter ? In-depth knowledge and real hands-on exp is matter.