Well, I can't answer that for you. You know yourself best. But what I can tell you is that one day will not make or break you. One day, one afternoon, one evening will not determine your fate. Studying for the bar exam is a marathon, not a sprint. It's decided over the course of months, not days.
A distance runner puts in hours of training every day -- six or seven days per week. But he also knows that his training requires rest and taking care of his body and mind. If he doesn't, he'll burn out or get injured. When it comes to training, you have to be smart. You also have to be honest with yourself.
In the past six weeks, you put in your endurance mileage by making your index cards and working through all of the law. Over the next three weeks, you'll incorporate sprint workouts into your mileage. Which is to say, by learning your index cards and applying them to targeted practice sets, you'll begin to finely hone your testing skills and understanding of the law.
So can you take off a night and watch the fireworks? You're an American - damn right, you should! Can you take the whole day off? If you do, simply plan accordingly in your schedule. But don't let the fear of falling behind deter you from having a little fun on the Fourth. Take a break, let it give you a boost of energy, and remember to smile. But be safe. No Frank the Tank!