This is, in part, why I don't advocate the ever-popular (on SDN, at least) "grades in M1/M2 don't matter" mantra. It encourages complacency in many. For me, at least, learning any and everything during M1/M2 helped me not only crush Step I, but made formulating ddx's and treatment plans much easier, and made studying for shelf exams and Step II even easier.
Especially during early third year, when attendings know you don't have any real clinical acumen, you get pimped on a lot of stuff (often minutiae) from the first two years.