Of course, every good student would do the work prior to taking the exam. Every quiz prior to the unit exam will help to prepare you to take the unit exam. Every homework assignment will help to prepare you to take the exam. ALL work in the unit must be completed prior to taking the unit exam. All work in the class must be completed prior to taking the final exam.
Always use the STUDENT PORTAL to check that you have completed everything in the unit BEFORE you take the unit exam. You would not be penalized if you were to skip the exams, but remember any exams not taken before noon on the last day of class would be recorded as a zero when your final grade is calculated.
Many students complete all of the unit work, then when they come in to take the exams, take multiple exams in one sitting. This is certainly allowed, just be sure you have completed all of the work in every unit before you take the unit exam.