If you are standing on the bow of a modern poling skiff, you usually stand with your feet parallel, straddling the keel, for balance and so as not to tilt the boat.
If the guide yells "9 O'clock", you rotate your head, shoulders, and hips to look left and prepare to cast... but you don't lift your feet to reposition to some preordained position, because doing so could make noise or send shock waves from the boat. Besides, you are now in a pretty comfortable "open" stance.
What if the guide yells "3"? Head, shoulders and hips rotate right, and feet swivel too. Now you are in a "closed" stance?
Or, is it an open stance for the backhand delivery? (Or open stance for a left handed cast?)
Feet do not define a stance... the rest of the body does. And you better be able to cast from multiple "stances".
What is most important is balance, and that comes from knees that are not locked... and like in rock climbing: you must keep your chin over your b***s at all times.