Many folks would argue that writing an essay is not the same as building a car. An essay written by one individual will always differ from that of another. Conventional Wisdom says "Essays defy standardization so of course there is no way to make writing them easy." As a result students believe that they must start from scratch all over again on each new essay assignment. The prospect causes great consternation. "What will I write? Where will I begin? If only there were some kind of essay writing system.
As any writer will know they are not the best person to look for any errors or omissions in their work. Read it through certainly pick up some obvious mistakes of course. However being too close to your writing is one of the reasons that book editors exist and of course the same applies to essay writing.
Once upon a time everything was made by hand. Each item had to be crafted individually; it took forever because there was no standardization. When Man grasped the concept of using patterns templates and molds to mass-produce identical parts for later assembly manufacturing efficiency took a great leap forward. Whether making furniture or automobiles once people had assembled the first model building additional copies was a piece of cake. They could be certain that the parts would fit together.