I passed the L3 exam last year, unfortunately, it was not my first try. I personally think this is related to the misleading guide of the schweser notes 3. I have to admit that schweser notes 1 and 2 are excellent excellent study materials, and I passed my L1 and L2 exams by only reading the notes. However, while I was applying the same strategy for L3, I failed! I found out that the notes 3 is way too simple regarding how they summarize L3 study contents and their mock exam questions are hugely deviated from the testing points that real CFA exam would actually cover. Given all these, my personal advice is, read your CFA books and make sure you understand all the example questions in the books and do the exercise questions after each chapter. You'll have much better chance to pass the exam this way. In addition, make sure you do the mock exam. This is a must. As for the old real CFA exam quetions, personally I don't think you should spend a lot of time on them as CFA organization cancels/revises their study content pretty much all the time, so some questions shown in the past exams may just be out-dated already. IF you are really fun of doing the old exam questions, make sure you understand the changes of the CFA books year over year.
Best luck to all of you!