My advice would be to read up on law school test taking - specifically IRAC'ing. Probably one the most important things you can learn to do come test time is know how to IRAC/TREAC etc., effectively. You will learn how to do this in your research and writing class, but for many, it takes a while to grasp. For the most part, it is those students who can write a polished IRAC analysis on their final exam that are going to do the best.
If the prof wants an IRAC-style answer, which not all the profs do. I did one practice question using IRAC only to find out there was no way I could get in the word limit using that method because it was just an IR question. The key to exams is being flexible and a)listening to what the professor tells you and b)seeing what the question itself is really asking for.
That's true, there are always going to be professors who want things done to their liking. But I think for the most part, professors want exams writing in some sort of IRAC form. Maybe not in second or third year classes, but I cannot imagine a Contracts, Property, Torts etc., final exam where a professor is not going to want or expect some sort of IRAC format. I think what most incoming 1L's do not realize is that most professors do not have time to read through every exam - rather, they "skim" through them looking to see if you touched on the issues. As such, this is partially why professors prefer their students to use IRAC'ing or equivalent - makes it easier on them come time to grade the large stack of exam papers, not to mention that it makes your essays have much more clarity.