You want to do things that propel the human knowledge and yourself forward. That's research. I did a lot of research during residency and also busted my ass clinically. As a result, my book knowledge (as in ability to recall random trivia) suffers. I am sure I will do poorly on a trivia heavy test, possibly even fail it, but the time I was able save by not learning random **** during my second year I was able to do research and improve my application. Of course you need to have enough knowledge to progress. I am talking about random trivia that you don't need to practice.
As a Ms3, none of lion's book will help you progress. Even knowing their name is a waste of time really. In fact, inefficient.
Effciency is doing the right thing at the right time to propel you forward. An hour spent on remember random crap as a MS2 worth more than an hour doing research as a MS2, and an hour doing research as a resident worth more than an hour remember random crap until third year really.