If you have managed your time well, and you have answered every question on the paper with a few minutes left what should you do? Metacognition may be the answer to allow the most efficient revision of your given answers.
In exams that have multiple sections, it is important to know how much time you are going to dedicate to each section. If a 60 minute exam has 2 parts weighted equally, then it will make sense to practice having 30 minutes to complete each section.
When opening up an essay style exam, it is very tempting to jump straight in and throw everything you know on the subject onto the page. The best answers are not necessarily the longest, but are well structured, and answer the question being posed. Following these rules will help you to do that.