For me it was not needed often but very ocassionally it was quite useful. It was not trained? Not sure what is there to train. If the autothrust is not reacting to a slow speed in approach you move the levers just forward of the climb gate and back into the gate. That wakes the autothrust up so to speak. Hardly rocket science. Crappy procedure? How do you know, presumably you have never tried it.
AB now recomends disconnecting the autothrust all together if it is not performing. Fine, but this also involves overiding the automation momentarily to match the thrust lever position to the current thrust before pressing the disconnect button. Otherwise you end up with a sudden rush of climb thrust until you retard the levers.