Written exams. In 3rd yr we have didactic courses basically 1 day/wk. Roughly 11 classes that meet once a wk. Some are a lot more difficult than others.... OMS, perio surg, implants, more pharm, more oral path, etc. The bottom line is clinic is exhausting in the beginning when you're treating patients all day. Tack on lab work for patients that you do after hours, stresses of requirements or competencies, and the simple fact that you've already been studying hard for the last 2 yrs, you just don't have the time or energy to study nightly for these classes. So, what ends up happening? Of course, you cram. Class-wise, 3rd yr is certainly lighter than the first 2 yrs, but considering you're in clinic/lab 80-90% of the time, you've got a lot of other stuff on your plate. A good example that I think is pretty universal is Part II of the Boards. You hear of 2nd yrs studying for several wks/mos in advance for Part I. Part II 4th yrs cram for (or so I've been told). Granted it may not be as important to you or as difficult as Part I, but part of it is lack of time or energy while in D-school clinic.