Although if you dont know it thoroughly its pointless. You'll skip the finer details.
I got to the point where I could immediately recognise eveything on an NMR, where it was, what it could be, the exceptions, etc. etc. etc. and I was guessing the exact questions that would appear on the unit 3 exam. I was right for most part, I just over-predicted the difficulty (I wanted something really difficult, much to my dismay).
But I didnt go ahead and do heaps and heaps of practise exams throughout the whole term. I did everything section by section, because it is more manageable. Instead of practise exams, do topic tests instead, such as using Checkpoints, Neap Studysmart, or the text book (I didnt like the text book ones but still a valid source)