not sure.. personally throughout my ACCA papers i have never touched the textbook except for P3 as that one my lecturer and his notes really cmi.
lecturer notes are usually based off the textbook anw, only maybe they simplify it for student's easier understanding. So logically, the contents of the textbook is sufficient for examination purposes.
However, my P1 lecturer which is Mr chee, his notes are very exam focused and is really based on the examiner's style of answering a qn, which is really great.
it is better to understand the concepts rather than jus purely memorising. but of course certain parts u need to memorise.