Hi Eric,
When I was preparing for the
SCJP I used JQ+ as a study tool like this:
1)
test one JQ+ test, it takes normally between one hour to one hour and half to finish each test
2) read the answers to each question very carefully, pay special attention to the ones I got wrong and the ones I guessed at the answer
3) go back to my Mughal book to re-read the chapters related to my weaker areas in the JQ+ test, and check with the API document and JLS for further clarifications.