Thanks for your detailed reply. Clarifies all my queries.
I really don't remember much about the Kaplan books, but I feel the Surgery one is the most useless, if I were you I would go through the pages very quickly looking for things you think are important for you to review and leave it at that. I would review cardio in the Internal Medicine one as well, just because cardio always takes the highest percentage of questions. The MTB books are useful for diagnostic tests, because they tell you exactly how to answer the questions in order, and also guide you in treatment, so I would focus on that and look elsewhere if you want to review a particular disease more in depth, because they are very superficial when describing clinical findings.
Also, don't read the Kaplan books or MTB more than once, unless you're looking for a specific thing, they're not like the First Aid for Step 1 which you can read twice or three times and actually get something more out of it each time.