Single engine, keep hand on throttle or power lever, if something goes wrong then you can reign in the donkey in front and not have any further surprises while you concentrate on landing.
Single pilot, ME, have heard different opinions, I think it is still best to keep your hand resting lightly on the throttle levers, like someone said, if engine fails, fly aeroplane, you have ,on pistons, usually 5 min max power before the remaining donkey keels over, so fly plane, Identify, Verify, Confirm, Feather and shutdown dead engine, then look after live one. Dont panic, but dont faff around either.
Multi crew, single or ME, have been doing 2 crew take-offs, in that pilot flying sets initial power, then pilot-not-flying sets max power and monitors engine parameters. This second bloke has hands on power levers and keeps them there until height reached for after take-off chacks and pilot- flying calls his levers.
Like so many SOP's and personal preferences, there are many ways of doing it, but I believe that in the event of an emergency, somebody should have honds on throttles to cut down reaction time.
