The legendary Mike Austin, whose 515-yard drive was the longest in competitive golf history, had a unique but very effective way to describe a square clubface which he demonstrated to me in his front lawn many years ago.
We went to the edge of his driveway which he used as the target line. Then he set the club so that the toe of the club was at the edge of the target line. Then he said “the clubhead is closer to the target line than the shaft, right?” I agreed.
The key, he said, is that it should remain closer to the target line than the shaft throughout the swing. When this happens there is an absolute minimum of shaft rotation on the way back and on the way through. And when shaft rotation is reduced, accuracy increases in a big way.