With this swing, you are not going to be actively retaining lag. It might appear as if we have held the lag to an observer, but that is an illusion created by the pivot.
Instead of holding the lag, you will actually be trying to get rid of it. You will throw the club with the right hand. You will throw it, against the tension of the left arm, out into the arc of the swing, like a tether ball around a pole. The left arm is relaxed but taut, as if it is a leather strap stretched from the left shoulder to the end of the club.
Once the throw has started, the pivot must not stop, or the tautness of the left arm will be lost, which will cause multiple problems. We must retain the taut left arm through impact.
The swing only has two parts. The pivot and the throw. The pivot moves the left shoulder during the swing. Our “leather strap” connects the club to the left shoulder. Then we throw the club around the pivot with the right hand. Done correctly, it provides easy distance and great accuracy.