First of all, congratulations! Welcome to the challenging world of getting things done in medical school.
(I'll apologize in advance for the length, as well as the many references to my experience - but it's the best way to describe what I learned trying to integrate GTD into my medical student study plans.)
I'll echo Julian's sentiments - the amount of memorization surprises and challenges almost every medical student. The shear volume of material is difficult to conceptualize until you're knee-deep in it - I certainly was unprepared. We joke a lot about trials by fire and "drinking from a firehose" - it's totally true, and it never really stops. My background coming into medical school out of college was as an education student - that curriculum fit well with very traditional GTD concepts - there were a lot of projects and assignments to complete, objectives were well-defined and actually sometimes useful; there was emphasis on understanding concepts and using analytical skills.
The first two years of medical school are generally NOT this way. Occasionally there will be a paper to write or a discussion to participate in, but by far, most of what you will do will be to memorize and to transfer the information in your lecture notes and textbooks into your head so that you can answer many multiple-choice questions. Yes, you need to understand the concepts from the basic sciences, but, in medicine, "concepts" are not big ideas as much as they are complex pieces of an intricate puzzle. I say all this because I caution you to avoid trying to break things down too much to fit nicely onto next action lists so that you feel like you're "doing GTD" - I wouldn't break things down smaller than the lecture level - there's just too much. (I don't know if you've started yet or how your curriculum was organized - I remember something like 3-5 hours of lecture daily, with miscellaneous afternoon labs or small groups - for me, this generated an equal or greater amount of time to spend studying / actively reviewing material for each day.)
If you read nothing else, consider this: the next action is usually "study." (As in, sit down in whatever quiet place you've created, open your materials, and go through them again.) "Actively review" is better. Most people find that they need about hour-long blocks. The goal is to put all that information back into your brain again (and again) until you understand it well enough to answer questions about it. There are a lot of different ways you can do that - you can make flashcards, re-listen to lectures, review notes, read the textbook, talk to yourself, whatever, as long as it works for you and is efficient. The "next action" concept works really well for me for the rest of my life, and it worked well for projects and papers, but not for weeks of studying in preparation for 3-4 big tests all at once.
(If you can't tell, it took me a long time to learn how to memorize and do traditional studying all over again. I tinkered with "how to learn _____" and wasted a lot of time. I did much better when I developed better discipline, skills, and tricks for just sitting down and working through the material, every day, rather than trying to organize it all in terms of concepts or objectives or whatever.)
Given all of that, you will be immensely well-served by the many good GTD habits you have - for example, you will find that you SHOULD collect, process, organize, everything else in your life - the project for ethics class, the email you need to send your professor about a question you have, the non-"study" projects you do have - groups to prepare for, the occasional paper to write, the summer research project to set up, as well as all of your personal life - if for no better reason that you'll be able to study better (and enjoy your personal life more) with all of it off your mind. Doing items from your next-action list is a productive way to make a break between long stretches of reading or listening. The weekly review will save you.
So here's the summary. If I had to do it all over again (and thankfully, I don't), this would be my action plan:
1. Collect ruthlessly. GTD provides a great framework for everything EXCEPT sitting down and working through endless amounts of basic science. Make your next action lists and projects lists, but don't try to break "study" down too much.
2. Block out several hours every day to sit down and actively review your lecture or reading material. (I recommend starting with lecture material, and supplementing reading only for what you don't understand or what you're directed to specifically look at. YMMV.) You may certainly refine your methods to your learning style as you go, but don't let tinkering get in the way of actual studying.
3. Take breaks. Short breaks every hour-ish, longer breaks after 2-3 hours. This is often a good time to knock out some Next Actions. Whatever you need to rest your brain.
4. If you need to block out time specifically to work on your next action or project list, you can. I highly recommend Cal Newport's Study Hacks website (www.calnewport.com/blog) for suggestions about how to transform the typical student's big, amorphous blocks of time into manageable studying, as well as for specific study tactics. (Specifically, look at the Autopilot schedule, Focused Question clusters, the Sunday Ritual, and, of course, Getting Things Done for College students.) (I'll warn you that a lot of the study methods are designed for other types of courses and may not fit well with medical school. And you will spend more time studying than any college student should.)
5. Review Weekly. At first, also use this as an opportunity to reassess how you're spending your time. Eventually, you'll settle into a routine.
Again, the sooner you develop good tactics, the better you'll do. And you'll use these for the rest of your career. (I just finished residency, am doing a fellowship, studying for boards, and expect to have an academic career. I'm still using a lot of the skills I learned from my first 2 years of medical school.)
Use this network - I, and others, are here for more help as you need it.
SYBaker [at] gmail.com