With the garments available today, there is no reason to have to get so bundled up that one can't keep good form.
I spot and stalk, I no longer wait for things to happen, so I am having to contort not only for the shot, but also to get into position for a shot, but I always do my best to maintain good form.
One can maintain good form bent over forward or backwards, standing or kneeling, laying down, facing up or down, etc.
Form is everything, because when that time comes where my form might have to be less than 100% to make a shot, my form will usually suffer less negative results than someone who has less than good form under normal conditions.
At least this is my take on it.