Malcolm Gladwell writes about the 10,000-hour rule in his book, Outliers. While I doubt I've spent 10,000 hours on any one topic, between my undergraduate years, MBA, and almost 3/4 (!) of medical school I have spent 10,000 studying. And like his examples, I've gone through several iterations of how I like to study.
I've had my notecard phase which consisted of buying paper drill (I ended up getting a modestly priced McGill) and calling Mead about the possibility of wholesale ordering their half-sized colored index cards after exhausting the local office store supply as well as Amazon's (btw - the paper drill was so I could use a book ring to hold them together).
I tried recopying all of my notes from class and texts into a single 3-ring notebook.
For the past year or so I've settled into a highlighter scheme where diseases are red, pharmacology is green, risk factors yellow, diagnostic tests blue, pathophys purple, and sequelae pink. There are also lighter colors that are associated with 2nd line drugs, tests, etc. I also make notes in my books (something my college freshman self would never have done) with ink pens of the corresponding color (most often Hi-Tec-C). While this has worked well, there have been some issues. Rather than carrying one highlighter, I need almost 10. I also need a similar number of pens. I also need a ruler so I don't write too off line in my books. In the end, I study with around $50 of highlighters/pens/etc. Rather than duplicating these items for all the places I study - desk, sunroom, school, couch, I use my bag-in-bag from invite.L.
It has 10 pockets that fit all of my writing instruments and are sturdy enough that I can store them in the tip up (for highlighters) or tip down (for pen) position. It has a handle built into the top which is nice. Other bags with handles on the outside tend to change the weight of the bag and can cause it to tip over. The bag-in-bag also has two button snap closures at the top which gives my inside pens a little more protection from jostling when I'm traveling. It's also large enough to fit a book or two and stands nicely in the bottom of my bookbag.
All in all, I think the bag-in-bag, though a more recent addition to my study style, will be here to stay.