Remembered a stick and rudder hero at my previous outfit who decided to fly manually with A/P, A/T off. He flew down to level off at Circuit altitude; unfortunately he forgot he had disconnected the autothrust and totally forgot to manually add thrust. The airspeed dropped to near stall speed before the sleepy eye PM noticed the f**k up, slammed the throttles up and saved the day!
With your hand on the throttle there is no way you will forget to add (or reduce) thrust. Taking your hand off the throttle while hand flying is a mistake made only by pre-solo student pilots and rank amateurs.