In respect of the questions/comment about all planes being unable to withstand the rudder being pedaled back and fro......or of it never being done.....and that no plane is tested for rapid reversals etc etc.
Take glider winch launches
If the speed goes too high on the launch you indeed do just that and pedal the rudder left and right. The a/c yaws significantly back and fro and the winch driver sees it as a signal to reduce the speed of the winch cable.
This is the official "too fast" signal on a winch launch.
So here you have substantial rapid alternating rudder deflections being regularly introduced when the a/c is flying near to the max manoeveing speed. Probably not stop to stop but certainly most of the way there.
I am quite well aware that transport aircraft are not in the same category as gliders but I'm just pointing out such movements are commonly used in one such class of aircraft.