It's true that downloading essays from the Internet instead of writing your own saves a great deal of time and effort, which you can then spend on other activities.
Significantly, you would not be alone in doing this as lots of people use downloaded essays. Reading a few essays to choose one does not take long and can give you an idea of the topic, and you know the essays are good as otherwise they would not be on the Internet.
It is important to say that doing this, however, does not help you understand the subject properly. It is also dishonest and unfair to other students who actually do their work. You may also be caught by your teacher and find yourself in big trouble.
Clearly, then, it is best to be organized, do your own research and write your own essays.