grandaddy..
ask one of the captains at lgw why you do the 3 sec control check. He ended up doing a left (right) only circuit at gatwick some years ago.
I believe that the rudders do not require a similar pause because they have a mechanical linkage to the pedals.
Airbus appeared to have some difficultyin agreeing whether when the flt ctl page moved it actually meant that the control surface had moved or the actuator that moved the control surface had moved.