I separate the archer's body in to 3 sections.
First: The "stance" is really the "support unit." We are naturally upright beings, and are most comfortable standing while doing something. We are most mobile and "reactive" standing. BUT, we can support ourselves on our knees, butt, etc. I think we should learn shooting standing then progress to other "support" schemes. The support unit is basically from the waist down.
The support unit is also the ONE piece that we usually set at the beginning and don't worry or think about it (or change it) for the duration of the shots we are taking at one time. Not really PART of the sequence, just an enabler.
Second the power unit. Basically the hands arms and shoulders. This is the real "meat" of the shot sequence. What we do to draw, anchor and release/follow through is the real shot sequence.
Third, the "control unit." Eyes and brain. This runs or directs the shot sequence, while the "power unit" executes the steps.
IMO, and ideally, the support unit facilitates your body's strength to execute the shot. A Square stance is pretty neutral to increasing your core strength and a good position for beginners. An open stance up to about 30 degrees allows the body to turn into alignment which is pre-loading your core and increases your natural strength. A closed stance makes you turn away from your center and decreases core strength Not real good and awkward besides.
Baring physical restrictions or injury, an open stance is not only good but highly recommended. A good way to LEARN how to get to your power unit alignment. Once you can achieve consistent power unit alignment and execution, you can play with other support unit configurations to make yourself more adaptable in various situations.
Arne