I've never seen anyone use a thermometer in Naples. It's either hot enough or not. Keep in mind that a true Neapolitan oven bakes just about right (top/bottom) and is very consistent. Not much fussing is necessary.
Re: Mix Times
Could it be that they are discussing hand kneading? That said, 20 mins isn't killing a dough with a proper fork mixer. A spiral mixer would probably be at it's limit at 20min though.