Haha, and here I had always thought
Wing Chun developed on canoes, while
Hung Kyun strictly came from flat-bottom skiffs...
Ok,
Hung Kyun Deui Chaak will mainly train your balance, as it's always going to test your stance and center through the bridge...
Necessarily, basic-level
Deui Chaak is "cooperatively timed", which offers both its strength and limitation. To train one's balance for a fight, where somebody is trying to break your timing while simultaneously imposing their own as "inaccessable", it is necessary to have a correspondingly advanced development, additional to such basic-level skills...
Best,
Michael