The advice my professor gave me for the bar (particularly with respect to the subject of criminal procedure) was to know the cases. Really know them. The bar doesn't allow you to bring in outlines and notes, so it's entirely a memorization game.
Law school mostly isn't. But then again, in large part the law itself isn't either. You'd be tempting a malpractice verdict if you ever acted without double-checking the language of a statute or case you were relying on. On the other hand, it's good to have statutes and cases queued up in your head so that you can know what might be applicable without having to research an issue from scratch. But that large knowledge base is something built by experience - something law students just don't have very much of.
For law students, law school is a way to get a lay of the land. To understand generally how the law works, and to get some insight into how specific areas operate. But the sheer volume of material we are exposed to, and the wide variety of topics that are covered, prevent us from building up large mental libraries of law. Plus the binge-purge method of progressing through semester after semester also doesn't encourage a lot of long-term recollection.
Still, things do stick to some degree. I'm continually amazed how much actually has. Now that I have some idea of how the pieces all work together, things I'd learned earlier are constantly being recalled and reinforced as I see new ways to apply them.
But looking back on my education, I wish I'd made more of a point to memorize more. I feel like I generally put more emphasis in thinking about how the law worked than remembering the specific mechanics. Now, given a choice, I think it's better to err that way. There's no point in memorizing a lot of specific rules if you don't really understand the principles of how and why they work behind them - at least not in the American legal system (in civil law systems the opposite may be true, and students are often expected to remember chapter and verse of piles of statutes). But sometimes I still wonder if I would have found my legal studies easier if I'd made memorization more of a priority.