This! Wilhelm was shocked behind the scenes.
There was no such scene in the script! Otherwise, the size of the shield and the diameter of the Giant Dragon's throat would definitely have been predetermined to ensure that the shield could get stuck in the opponent's throat.
Seeing Aske's decisive and unhindered movements, it was likely he had already calculated the size of both to confirm that the shield could get stuck before proceeding, otherwise losing the shield and being completely engulfed by Dragon Flame would certainly mean a total wipeout and a reshoot!
However, aside from the size of the shield, when had he confirmed the width of the Giant Dragon's throat?