While this varies from one student to another, my expectation is that you will spend at least 2 hours outside of class doing reading for each hour you spend in class and lab. That means you would spend at least 9 hours per week in addition to attending class and lab. It is my observation that there is a strong positive correlation between regular class and lab attendance, staying current with reading and lab work, and final grades in the course.
In my country, we spend atleast 7 hours in a class, that also depends on the day because there are some students that has their schedule almost the whole day and even continues at night. I can say we spend 1 to 2 hours outside the classrooms which leaves us to work with our school works at home with atleast 2-3 hours, it is really a hectic schedule.