My son use to have to write sentences (he is 9) but now we started doing pushups and different exercises. Now he has all this muscle and actual enjoys exercises, even doing it on his own now that he sees results. Makes punishment easier now. I guess I am the only one who thought the essay was ingenious. However after the fact, a good, honest, CALM talking to should follow up. While mouthing off and punctuality is something a parent can easily notice, other problems like sex or drug use you may not know. You want a child to come to you but there does need to be boundaries and punishment.
First thing first though is a parent cannot fly off the handle. Second the child has to be aware of the rules and what the punishment will be, and enforce it. This may be an issue you can discuss with a child so they are a part of the rule making and punishment making process. It helps them feel they have some input and control. And of course once you do it that make sure you enforce those rules.
However I do not have a teenager, just know what it's like to be one.