IELTS 15, 14 & More: Difficulty Levels, Overlap, and Preparation Guide

Yes, the books in the series 'IELTS 15', 'IELTS 14', and so on are arranged based on the level of difficulty. The books in the series cover different aspects of the IELTS exam, such as reading, writing, speaking, and listening. The number of books in the series varies, and new editions are released periodically to keep up with the changes in the IELTS exam.

The books in the series do overlap in curriculum to some extent, as they cover the same basic skills necessary for success in the IELTS exam. However, each book is designed to provide students with new materials and practice exercises, so they can continue to improve their skills and build their confidence.

It is difficult to say how many books you should read to get a 6.0 or above in the IELTS academic test, as this depends on your starting level of proficiency in English and how much time and effort you are willing to put into your preparation. However, working through several books in the series can certainly help you improve your skills and increase your chances of success on the test. Additionally, it is important to supplement your reading with other study materials, such as online courses, practice tests, and language exchange programs, to get a well-rounded preparation for the exam.