I used them during my Kaplan course, I carried them around with me all of the time so I could go through them if I had a few minutes. They worked great for me, although I wish I had looked at them more! Using flashcards is my favorite way to learn stuff though, so I may be biased. I like to take out the ones I know as I go through them, until I know them all.
P.S. This never happened with my MCAT cards. 😛