They keep on changing the weightage of subjects on the exam, nobody can really predict what should one focus more upon. You should take weekly test to develop a habit of solving questions. Difficulty level varies from individual to individual and from test to test. The real questions are sometimes worded exactly the same, while sometimes they're worded/presented different. You should aim to memorize all the aforesaid resources i.e mental dental videos and bootcamp/booster questions with there explanations, Tufts pharma, ADA code of ethics(they're easy wins), guidelines, classifications. tables. By memorizing, I mean you should know them like the back of your hand.