A bit controversial title, just copying the title of the YouTube video I happened across. A bit alarmist in nature but there is some genuinely good stuff with regards to the "cone of learning" and why reading books cover to cover 3X-5X and still failing with test takers wondering, "what did I do wrong." There is an interesting bit at the end, the trainer asks for $499 from you to coach you through the exam prep and will cover the cost of the exam if you fail. If this was already posted, apologies for the repost.
https://www.youtube.com/watch?v=b87yfzOwzxc