Not only does it depend on the person, it depends on the course, even down to the lecturers. I attended the majority of classes for anatomy, embryology/cell bio, neuro, and psych because they had pretty good lecturers and I was interested and able to stay awake in class. I skipped pretty much all of biochem and immuno, and all of the non-science courses like biostat, ethics, and behavioral med. My school does audio recorded lecture with the PowerPoint so it's not a big deal to miss class, but you definitely have to be more disciplined with keeping up on your own. Just try it out, you'll figure out what works for you.