I attended two last year for Level II and it was a bit of a hit or miss. Even though I was already familiar with most of the concepts I decided to go as a refresher and found the Kaplan quant session to be very useful. Generally they don’t cover everything as it tends to be 1 - 1.5 hours, but they usually touch on some key points and, at least for Kaplan, they tend to throw in some good tips. The other one I attended was covering Financial Reporting and it was not as useful. The presentation was boring and confusingeven for things that are not difficult.