In my experience, I've always learned a lot more during the class than was tested on the exam (except for intro classes). I'd personally prefer easier exams but

In my experience, I've always learned a lot more during the class than was tested on the exam (except for intro classes). I'd personally prefer easier exams but harder assignments and projects that allow for some collaboration. If you were allowed to test out of classes then the exams would need to be made a lot harder so it includes all the material you should have learned if you took the class.