The material you get is important and will be useful one day to prepare yourself for an interview, but the question banks are almost more important than them to pass the exams at the current stage. And this is to blame to EASA. Too many questions are too ambiguous, too often it's unclear what the examiner wants you to reply or what regulations he is referring to (ICAO Annex 2, EU-OPS, SERA, etc.).
TL;DR – question bank, rinse and repeat. All 14 the subjects.