"Rice paddy prone".
FWIW, if the precision shooters thought there was a way to get a more accurate position, they'd have adopted it. Biomechanically, I can't see how balancing on two ankles can be very stable. Spreading the load across a knee (or two) and bent feet is much more stable. Even more so, get your arse on terra firma , two feet out in front and put both elbows on them.
In my whitetail experience, many were shot standing with the elbows out. Others have been shot from either a sitting or kneeling position. Stable to get control of my breathing, weight of the rifle on bones not muscles, and high enough to see over the snow or tall grass. One was taken at 350yds too with a 300 WM.