People are just different, so you cannot really say how much time one needs. It all depends on commitment, focus, and a little bit of luck in the end. I passed 3 out of 3 with relatively below average preparation: Level I-around 60-70 hours, mainly Flash Cards on the subway, and Ethics from the Schweser Notes, Level II-around 40 hours, mainly past exams and Schweser CD with exams and problems, Level III- around 300 hours, all from original books and Flash Cards. So, as you can see, everyone has to decide about what is affordable in terms of time, non-time constraints, and finance/non-finance background.