When I did my atpl-theory, we were the first class on a "new" QB.
I was the only one to pass POF (out of 20 people in our class) because I did study. The rest failed (QBs). I got 87% or 89%. No QB at all.
For the next sittings, I did use QB, but as a supplement. It is a great tool if you use it right.
My advice would be to STUDY. A LOT. And then you use the QB to check your knowledge and learn tricky questions/understand what kind of answer they are looking for.
For each subject (before the exam), I covered around 90% of all questions. Some of the questions I have done 4-5 times (if itīs hard q., Iīll mark it "for review" or something).
At the end, I ended up with avg of 92% and great knowledge.
Most of the companies have ATPL test for an interview. Then there is an oral exam as well. Later on, youīd have to do a TR, company procedures, etc. Basic ATPL knowledge helps a lot.
Why would anyone waste 6-12 months memorising 14000 Q&A and "study later", when one can study right away?
As for technique - whatever works for you. Itīs very individual. Read books, do practise questions (QB), read explanation there, comments of other users. Watch youtube, ask questions here.
If there is one question you donīt get - move on, come back to it later. Or just memorise that one and move on.
Good luck!