It is a matter of personal choice. If you think that you can prepare at your own and have the necessary guidance available, it is not necessary for you to join. In case you need to focus on things and you find it difficult to get the required push by a learned and well qualified instructor, it is always very helpful to join an academy. So, now the ball is in your court and you have got to play it the way you want. In my personal case, I had joined an academy and it helped me a great deal. It may be or may not be true for everybody since I have seen many fellows passing this examination without coaching.