In the Catholic faith, the only one I can speak of with any knowledge, a confession is not valid without the genuine desire and intent to discontinue the sinful behavior. Some people do have to confess a sin multiple times in life, but if his understanding is that he can do whatever he wants with the plan of confessing it to somehow play the moral system, he is mistaken. As you are implying, in this way he is just using the confession process to justify his choice to sin, which I believe is an additional sin, as it is a very dishonest practice.
