I think Book 7 is frustrating in the way of its freaking wordy questions and answers, multiple stems of questions format. Tonnes of unnecessary information are given.
BSAS seems easy in its question format (I gaurantee, it has less than half amount of words if compared with book 7), but the questions are more tricky.......
If you want to train your reading skill, book 7, especially the ethics part, can help you to scan fast.