I’m not sure where all this advice is coming from to take the test before starting intern year. ALL of my intern class of 12 took it in November, and our program reimbursed and allowed time off. I honestly don’t believe I know a single person who took it before residency, unless it’s an IMG with different circumstances. Certainly none of my friends or acquaintes from medical school took it early, we all went to the beach in May instead and enjoyed life before it got crazy.
Translating passing Step 3 into solid preparation for intern year is a stretch at best. That being said, since clinical responsibilities as a medical student tends to be pretty low, so intern year will help acclimate you to what is important in your patients day-to-day.
In anesthesiology no one gives a crap about Step 3, just need a pass. I imagine most fellowships are the same (MUCH more important - in training scores).