I agree with Piltdown Man. I saw many a student (mainly middle-eastern sponsored students) not do a scrap of work, but cut through 500 or so Bristol questions every day. Safe to say, some failed miserably. Even comms.
I reckon the best way to learn would be under an instructor in a bona-fide ground school, highlighting the key points in the textbook. Go over the content in the evening and summarise your highlighted points by making footnotes. If you're lucky enough to have questions in the books (like the CAE Oxford books), do those after each chapter. If not, try to refine a search on BGS to what's specific to what you've just covered. If you get any wrong, don't just tick the correct box and think "I'll remember next time...". Make a point of going back to the text and reading why you had it wrong. Maybe even highlight it in a different colour. With this method I think you get a lot of information in your head to fall back on, whilst learning how to tackle the horrible, snidey questions that do pop-up. That's what I did anyway.
The worst example of quite literally learning the question was a very common in Air Law. In the question was a description of a certain type of airspace, the aim to determine which it is, and we were taught to count how many times you see the words "VFR" or "IFR". From how many times you saw these words in the question, you could work out which was which by just remembering the rules. Class C was 8 times, Class D was 6 times, E was 4 times, F was 5 times, or something like that. Please, god, don't quote me! It was the worst demonstration of teaching and learning to exams I saw in ground school. Bloody funny when it came-up though !
With the old questions, you had the ability to just hammer the question banks and still pass. The new-style questions force a student to actually learn the content, which will no doubt take much more time than before. When I was at ground school, even with the question banks, it was studying nearly ever day for six months to get through all 14 exams of the ATPL theory. I could count on one hand how many days I had off without opening a textbook in that time. Could it be the case that the length of groundschool needs to be lengthened to fit-in more study time?