There is no harm in using different books to improvise your studies. But there is a reason why we have books named as “study texts” “study guides” “text books”.
In CAT and ACCA qualification we use term study text to mean such books which are written by official publishers according the syllabus of a particular subject. And that is the main reason why even teachers, most of the time, use the books that are specifically written for the subjects. This also avoids getting involved in such topics that are not going to be examined.
Another fact to understand is, different books might have the same topics, but they might have explained the topics in different length and breadth or simply saying having different scope.
For example, T4 of CAT qualification and F2 of ACCA qualification have process costing in their syllabus. Now, one might think that we can use books interchangeably as both subjects are about costing and also talking about the same topic. But T4 syllabus does not contain computing process cost under the situations where we have work in progress at the start of the process. So, if you are using F2 book to prepare T4 exam then you might be preparing one topic that is not going to be examined thus, waste of time. And if you are preparing F2 and have used T4 book, then you will have to face problems as you have not prepared the concept that was part of the syllabus.
My advice is that if you have a really good idea of what is included and what is not included in the syllabus than you can go for any book at all. But if you think you will not be able to pin point the syllabus requirements for particular topics then use the study texts written for particular subjects.