I have a launch day Series 6 (4 years old) with 78% battery health, that I wear all day everyday, and charge in the evening for 30 or so minutes. So it easily l

I have a launch day Series 6 (4 years old) with 78% battery health, that I wear all day everyday, and charge in the evening for 30 or so minutes. So it easily lasts 23.5 hours and by that point its at around 25-30% battery life. I genuinely cant understand where the 18 hours they predict come from!