As I said, most recommend each hour of lecture time to be followed by three hours of self-study.
Also, if someone is going to do those three years of non-class study (after class in my case) so they can have my equivalent non-class study - why not just do the extra year of in-class work and get the diploma? The attitude perplexes me - "I will study three years like you, but won't get a diploma that will help in employment".
No one is forcing me to go to class. But if I am taking a class on theory of computation, with quizzes etc., then it makes sense that that will be the months in which I read about pushdown automata outside of class. So after I choose which class to take in a semester, I am in a sense "forced" to study that topic outside class for the next four months. I can also e-mail my professor or classmates or wait after class or go to office hours if something confuses me.
2) You will have gaps because you missed things
3) You won't retain the knowledge as well because you won't be tested on it.
4) If you're someone who isn't good at math, good luck motivating yourself to study real analysis, optimization theory, statistical learning theory, etc.
If I am paying money for class, then shouldn't I be taught the material? Not do something I can do for a free 2-year stint with a computer.