My assumption is that the teacher should optimize the class on the amount of the course material the students learn, and how well they retain that knowledge. As far as I can tell, the goal of all of the teachers I know is to get the students to learn the material the best they can, so they structure the class around that ideal. I fully understand that some students just want the credit, or to just get by with whatever they deem to be sufficient knowledge, but I don't think it would be generally beneficial to structure the class to give them incentives to do so.