When teaching the class, some instructors would break it up into 4 four hour classes offered during the week or two 4-hour classes during the week and one 8-hour on the weekend. Instructors do try to work with their students to make it less difficult to get in the 16 hours. As others have said, the class time may vary depending on the number of students and the skill level. I have had carry classes where no one in the class had ever held a pistol and the class took a lot longer than 16 hours.