This book is just similar to the other 7 books. The problem is simple; it provides "only" 4 tests, with some model answers. There is nothing to help the student. This book makes a lot of money by cheating students and providing very little. I would recommend a book like Test Builder 2 instead because it can provide the model tests, but provide methods on how to work on it.
Sorry Cambridge, but you have to adapt to the times... but actually, you don't... because people will always buy this book.