#4 (IMO) they are essential to building up your “exam endurance”. The ability to sit down and focus for 6 hours and perform at a high level doesn’t come naturally to a lot of people. You could understand the content 110% but if you can’t focus long enough to deliver the info in the format presented…you could be SOL!
As first time passer – to pass first time, you need to do all the practice exams (10+), EOC questions and Schweser questions. You also need to redo the ones you got wrong a few times afterwards. Plus carefully go through box examples in book (they test you on that). Oh and know everything in the official books, as they really like to test obscure bits at CFA. And I have no idea how the written part of L3 is marked, its odd.
At L2-3 its way more than 300 hours to be certain of a pass. At 300 hours, you’ll probably fail unless you’re lucky or seriously good (and not unlucky).
Ethics – it scares me how people find it hard. Each question can be answered if you ask yourself: “what would a decent man/woman do / not do?”. I found it was free points.