From my experience so far, I've no idea how you would pass these exams without the question banks. I would go so far as to say that when you are studying for these exams you will imagine that passing the exams and understanding the material seem to mutually exclusive objectives.
I don't want to sound arrogant, but I'm a university graduate with good grades and mathematical ability so where am I going wrong?
I think that gaining a good understanding of the ATPL theory will be something that I will have to continually pursue throughout my career by combining the theory with practical experience.