I really disagree with this. I think this is how it should go.
Diagnostic > Powerscore Bibles > Several practice tests to find weaknesses > Tutor to address weakness > Fine-tune your strategy by banging out as many practice tests as possible.
Combine the last two and I agree. Anyone prepping should also take note, Powerscore only uses real lsat questions, and the best prep comes from using real lsats, so make a note of what tests you are answering questions from in powerscore (they list them at the end) and do not use those tests for your simulations. I made a customized computer assisted feedback to help me analyze my tests. PM me if you want info on how to get it. You will better understand your weaknesses after you have taken and properly analyzed a number of practice tests (at least 5) to see consistencies. I have put together a strategy and tip sheet that helped me improve from a 144 to 161 as well as what has helped me in this admissions process. Feel free to PM me if you want this info.