4 weeks at 8 hours a day, as long as you were paying attention first year. A lot depends on the person, but I assume that if your goal is to get 95+, and you put up a survey that doesn't contain less that 4 weeks as an option, you have already spent considerable time learning the material in school (and consequently received excellent grades). For those people, it is "easier" to earn 95+ because they have put in the time up front, and a larger percentage of the material is review.