Is it better to use one book or
many books for each subject
Using just one book is much more effective use of your time as compared to using more than one book.
Which book to use? Or, which book is the best?
Most of the books approved by an education board, a school or a college are usually good. You should talk to last year's students. Find out their comments. Look at a few text books. Compare one chapter from these books. Then decide which one text book you want to use.
Some students feel that they may miss something by using only one text book. But it is not true. Subjects which are calculation-based (such as Mathematics, Physics, etc.), the numerical questions may be from different text books. But the difference is only in the numbers used in the questions, not in the concepts. It is better to spend more time on one text book than to divide between two.
I consider it a total waste of time to use more than one text book.
So, is it clear now?