For those that have taken and succesfully passed the Excelsior Organizational Behavior exam, how much time did you dedicate to studying?

I plan on using IC, the practice exams, and the Stephen Robbins book Essentials of Organizational Behavior. I typically study 3 or 4 weeks for my exams, but since this is an ECE exam and upper-level credit, just thought some of you may have an opinion on the amount of time needed to pass the exam.

Thanks,