being kept at 100% is much worse than ideal
This is at the heart of my laptop battery experience. My laptop is rarely off AC power. When I had the charger set to stop charging at 100% (and to recharge when 90%), my battery life greatly improved. OId battery dropped 60% in reported capacity in less than 2 yrs; new battery is barely down 30% in the following 4 years.
I call it Chinese electron torture for your battery -- drip, drip, drip.