Cheating isn't really a problem that teachers should need to deal with. By punishing a student in grade school for cheating, that student will learn the valuable lesson of not cutting corners. In my years, I have seen alot of blatant cheating even things like answers being passed through the room. At some point you will notice how quite a few teachers don't give a damm if you cheat (as long as it isn't to blatant) as it won't affect their personal lives. However if they do punish a student, it will affect their lives as that student will hate them with a passion. This might even cause a chain reaction where his/her friends also start hating the teacher. Eventually the friends of friends will also assume that the teacher must be really bad due to all the rumors which could eventually cause the teacher to be evicted. That is an extreme example but it could definitely happen.
In the end cheating on tests will make you develop the habit of cutting corners. You'll fall into the mindset of why should I learn for a test that I could cheat on. In the end you would have wasted your time in a class you were never interested in.
Think about the consequences of successfully cheating something more important like a degree in something. Now you've got a worthless piece of paper that will help you secure a job in a department that you were never interested in.
In the end, there will be times where you won't have enough time to learn due to some important reason. And even in those situations, I believe there are definitely ways to just take the test at a later time because either your reason was good enough, or you can always just call in sick. In doing so, you will force yourself to learn as cheating off your classmates would be impossible and to create a cheat sheet, you would need to learn the content anyways.
On a side note, don't call in sick on the day before every big test just to get more time to learn. It doesn't matter who you are, this will negatively affect your future test scores as:
1. you'll being missing a ton of classes that you'll need to make up
2. you won't use the whole day to learn because if you were that motivated, you wouldn't need to fake a sickness
I just felt like adding that last part since one of my friends was exactly that type of person.