Passing the exams is one thing. I'm inundated with applications from people with the basic qualifications at the moment.
Demonstrating adequate knowledge at interview is another.
You may all rest assured that, like my colleagues with whom I interview, I can spot someone who learnt the question bank, from a hundred miles, on a dark night, in fog, with one eye closed and the other watching the X Factor (God forbid).
There is no substitute, in exams, interviews, or professional flying, for a sound fundamental knowledge of the subject matter.. To progress into training or management, you need to know the basics inside out.
I hope that's clear!
(...as for 'learning by doing the question bank...'. He's done it again!)