The best way to make sure your address position is perfect is to base the setup around the ball. I make sure my students use the golf club as a measuring tool. Our eyes give us incorrect information each and every day. I try to instill a pre shot routine where the student sets the club down behind the ball and builds their stance around that. People that set their feet first struggle to get a consistent distance from the ball.
Once they set the club behind the ball then I ask them to let their arms hang freely out of the shoulders. The last part is I ask them to aim the shoulders to give them the correct shot shape. The shoulders are so much more important than the feet so this is the LAST thing that is set in the setup. Go from most important to least important.