Actually, guys, I'm surprised every day by just how much of what I learned in the preclinical years is relevant and important.
Every day I come across more and more of this supposedly 'inessential' material - on the wards, in tests, in random questions asked by patients and pimping sessions from attendings.
The more of this stuff you guys can remember, the better. Don't goof off.
(And yes, you will forget a lot of it. Then you'll be rudely surprised when you realize much of residency is relearning the random stuff from medical school you forgot and adding an entirely new dimension to it. Medical practice is actually more than what you learn the first two years of medical school - but it includes most of it as well. It's not just 'learn and dump' for medical school and start over fresh for residency. Medicine really is everything.)
Agreed. Even if you have forgotten, it is easier (and quicker) to relearn. You may not remember calculus, but if you have the opportunity to review it, it will come back to you more quickly than if you were learning calculus for the first time.
As a practical example, I occasionally have premeds shadow me when I round. Despite their basic science background, it takes a lot longer (and more confused look) when I explain the concept of anion gap. And for them, it's more of a "ok, cool". If a 4th year Sub-I (in the ICU) is on the team, then I can spent more time discussing the finer details of analyzing the anion gap (and what we should do about it) - from recognizing it in the first place, to discussing differential and causes, and how to fix.
If you don't have a background in physiology, then explaining cardiac output, pre-load, afterload, SVR, etc would take longer since you're learning it for the first time - and explaining why certain vasopressors work better in certain situations than others (based on their targets, etc) would be harder if you are learning cardiovascular physiology for the first time (information overload).
The clinical years is when you get exposed to the practical side of medicine, and residency is when you learn how to use your knowledge. But before you can begin to compose an essay in a foreign language, you must learn the words and grammar first.