The bar exam is one of the toughest tests conceived, probably equaled only by the CFP™ exam. While the test's length and content will vary from state to state, it will always be an exhausting marathon of typing or writing, requiring your recollection of three years worth of dense legal principles.
Fortunately, after three years of studying, outline building, and essay writing, you will be well prepared for the tasks required, and as long as you prepared adequately, your biggest problem will be finishing your perfect answer within the time limit, rather than struggling over spotting issues or outlining answers; these two should be "muslce memory" by now.
Developing these necessary skills is relatively easy. If you develop a method for essay writing, outlining (such as I did), and use it during every assignment during law school, you will already be well prepared for the bar before you graduate.
Of course, there will be a lot of cramming the few months between graduation and the bar exam, but this is where all of those outlines you made, and/or the outlines from a bar prep course, will become very useful tools with which to practice essay questions.