Is it bad to charge iPhone if its at 80%?

Is it bad to charge iPhone if its at 80%?

Nope

Not at all.

No I run mine down everyday. Charging is a pro active measure to sustain a battery. Also remember running the battery low every now and again is good also.

Not necessarily if it's every now and then, but Apple does suggest to charge the phone from low battery (0 to 30%) to 100% most of the time

No… Just don't do it a lot

Why would it be?