I think much of the stuff in PLSII is somewhat obvious. Take the way that you are taught the law for example; I think it is very clear that several tests in a semester where you actually get some feedback would be better than no feedback and only one test per semester. This type of system allows the student to improve and evolve in his legal thinking, etc. A one test system where people don't even get comments on their exams seems like it would only lead to confusion for students. They may know they are not getting it, but without being helped to understand what they did not get they seem doomed to merely repeat the mistakes of the past. It certainly doesn't seem like the best way to teach someone something, and I think it says a lot that no other type of graduate program teaches that way. Grad students get copious feedback about their work. Even medical students, where the entering class is similar to that of a law class, have about 10-16 tests per semester. I think it does come down to laziness for professors. They have a system that favors them rather than their students and why would they want to change that?