Thanks for your response!
BGS do allow to sort by topic which I've tried to do but still, some questions are definitely 10 lessons into the future.
I guess what I'm trying to ask is should I be learning or revising from the QB?
If learning, do I just note down all these random explanations (that explain why the answer is correct, no problem, but I have no understanding of the wider picture).
If revising should I burn through the whole module to have some background knowledge, THEN attempt the QB?
sorry for the long reply