Your friend’s soldering experience may well be much more at the 10W/delicate/circuit components end of the spectrum, whereas the mighty NACA5 is made of sterner stuff and needs rather more intense treatment. Certainly the ‘leccies I know laughed out loud when I said I’d been recommended to use an 85W iron - one even queried whether such things existed.
I’d certainly show your chum the excellent advice and pictures in the FAQ before starting.
Mark