I have noticed with both lightning and macbook chargers that high current draw (and associated heat) while the cable is bent seems to be associated with the cab

I have noticed with both lightning and macbook chargers that high current draw (and associated heat) while the cable is bent seems to be associated with the cable degrading. Not using the phone while charging negates this, as does having the cable flat on a table when using the macbook (as opposed to using and charging with the macbook on your lap, where the cable rops down immediately).