But how can that be, the wings are attached to the aircraft. They must go with exactly the same speed??
if you hold a model stationary and "yaw" it one wing will move forward the other backwards, so they are NOT going exactly the same speed, especially at the wingtips there is a speed to be added/subtracted from the aircraft overall speed.
When you speak about the wing goes faster you mean the wing goes faster during the yaw? But when the yaw is finished and you just hold the yaw in place with rudder.What keeps the roll to continue now? When both wings move equally fast?
If the yaw is finished there is no more roll - if you are "holding the yaw with rudder" you are
still yawing!