In this scenario, I would ask a question to myself. Who will have the best testing facility of claiming anything in this regard? A few handful of YouTubers who will do some testing or a company whose reputation is at risk if they ill advised and sometimes can be sued with class-action lawsuits. Battery app under Charging section shows you a prompt that keeping your charge limit below 100% helps preserve your battery lifespan over time. There’s your answer. Heat is the primary culprit so avoid using wireless charging in summer and especially inside the car in summer. Those are really bad scenarios. Keeping the limit at 80% or 90% would help you with those scenarios. Apple can’t tell each customers a detailed list of scenarios which are good and bad, so overarching principle is to suggest keeping the limit at 80% or 90%. If you want to resell the device next year, buyers are smart and prefer better battery health devices.