Although the conclusion paragraph comes at the end of your essay it should not be seen as an afterthought. As the final paragraph is represents your last chance to make your case and, as such, should follow an extremely rigid format.
The most important part of writing an essay exam is ensuring that you`re answering the question was posed. Even if you made sure you were interpreting everything correctly before you began, you may have forgotten to address a subquestion or integrate an example as you were writing. Before you submit, read the prompt again and make sure your completed essay matches up!
However, this thinking process does not reflect the reality of the situation. In fact, even if your teacher hasn`t given you any hints about the essay question, you do know what it will be about: the concepts and ideas you`ve discussed in the course.
For this reason, it can be helpful to simulate the conditions of a timed exam before the actual day: pick a practice question, find some lined paper, set a stopwatch, and see how you do!
Unless if you finished way ahead of schedule, don`t worry about major revisions like reorganizing the structure of the essay–it`s better to hand in an essay with an imperfect structure than a paper that`s impossible to follow because you had to stop halfway through the revision process.
The writing process of preparation, writing, and revisions applies to every essay or paper, but the time and effort spent on each stage depends on the type of essay.