You must not fight too often with one enemy, or you will teach him all your art of war.

Every time you go at the same person the same way, you show them how you think. They learn your openings, your tells, the point where you soften. Repetition is instruction, and in a long-running conflict you are teaching for free. The same holds for an argument you have had twenty times at home; by now the other person can run your side of it.

If a disagreement keeps recurring, assume your usual approach has already been studied. Change the terms rather than the volume: ask a question instead of making the case, or let it rest until the pattern breaks.