As one of the other threads recent threads (http://www.lawschooldiscussion.org/prelaw/index.php/topic,3806.0
) has been discussing, this isn't really a decided subject. The feelings seem to be on both sides. I really don't see anything inconceivable with doing well without ever prepping. Maybe they've had similar classes in undergrad, maybe they picked up on the game quickly, maybe they're naturally a good fit for law school exams, or maybe its something completely different.
Regardless, there's no one who has been able to show definitive proof that studying pre-1L summer is necessary. Of course on the other hand others will say that there is no definitive proof that studying pre-1L is unnecessary.
Perhaps the person who put it best was a 3L I talked to at admitted students day at NYU, who said something to the effect of this: Law school is a game with imperfect information. There's plenty of people giving information, but you have no way of knowing exactly what YOU will do when you get there. No matter what you've done before, you've never taken a law class and you've never taken a law final. And no one elses experience can provide perfect information to describe what will happen to you if you do this or don't do this. So take all information with a grain of salt.