It seriously takes a lot of work. The thing I find most frustrating about PBL is the uncertainity of your focus. It's impossible to grasp every component of the topic, and not knowing what is the most important is difficult to determine. You never really know if you are learning what you need to know. I go to Case and it's hybrid, so fortunately we have lectures that kind of direct the PBL. The lectures are not always lined up with the PBL so you find out later where you should have focused.