Harm here is usually not a single medical event. It is hours gone, skipped obligations, a foggy next day, and a rising need for more extreme or longer sessions. Some people also notice worse real-life arousal. None of that requires you to be “the worst case” before you are allowed to stop.
If it is occasional and you can take it or leave it, you would not be searching this hard. Use the stop plan: ritual, urge, streak.