If we read more than one book on a particular topic or a subject, we will have the following advantages:

1. We will learn more.

2. We will get more than one styles, views, interpretations, examples, explanations, diagrams, techniques etc.

3. Our SSL time, comprehension and understanding will increase.

4. Our ability to correlate and associate different study materials will increase.

5. It will improve our vocabulary and expressions.

6. We will have more choice for our notes taking because same topic is either shortened or enlarged in different books.

7. It will give us better results to improve our creativity by having many associations of thoughts for a particular topic.

Studying more than one book for any subject is highly useful in higher classes and at any level of learning, in general.
But whether self-study, notes taking or preparing for the exams, it is better to start with one book, because it will lead general understanding of the subject matter.

The alternative to it can be that we read a chapter or a topic (not less than that), in one book then try the same in some other books. It is similar to learning and mastering a method or technique. It gives the feeling, of "mastering" something, this mastering can be applied to other fields, areas etc.

Without mastering something, it is not possible to master anything. It is quite different to know something and to master anything. It is quite different know something and to master something. Knowing anything is very simple, perhaps natural.

For example, it is easy or simple, perhaps natural. For example, it is easy or simple that we know that pilot controls an aeroplane or we may know everything he or she does in the aeroplane, but will it make us a pilot? Not at all, you see it is not possible. It can only help us to master the skills, methods, and techniques to be a pilot. Perhaps, we may be able to transfer our mastery in any field of our lives.

Thus, reading more than one book for any subject is highly useful.