There was a time (when I was an active JW) that I was embarrassed when I hadn't studied my WT...with good cause (at the time) too. JWs are a judgemental lot. You just knew that people saw your virgin magazine and would consider you as unworthy of Jehovah's spirit since you couldn't take the time to be prepared for his loving provision of regurgitation. Admit it...you did it. I did it too (when I had prepared)...
But as I started to realize what a sham it all was, when I did bother to show up, I proudly held up my unstudied, un-underlined, un-highlighted magazine. It didn't take long to realize that you didn't need to study ahead. All they did was read the paragraph and repeat it. How hard is it to keep up with that, even if you had never even seen the article before?
Toward the end of my somewhat active status I stumbled on a little secret... our WT study conductor never studied ahead. His copy was never underlined, never marked up with notes, not even creased where it was folded open. He just kept up with the reading, asked the question, took a supplemental answer, read any scriptures not quoted and moved on. If you think about it, you don't have to prepare to conduct the WT study. All you're doing is reading prepared questions to a pre-printed article and you're not allowed to introduce any independant research, so why bother...