3 days of battery life

I think it's apps like Accubattery that contribute to this "charge it up to 80%" mentality. Frankly, I personally don't even think about what scientific evidence may point to this. All I know is that if it was making a difference - the chances of it making a material difference before I trade or sell the phone is minimal.... and I bet that goes the same for most of you, too.
Yup. I don't waste even the slightest thought worrying about charging practices. I charge at night, I use by day, I enjoy my phone. Never been an issue for me before, and it's not an issue for me now.