Level and Secure the Entire Door Frame

What happens here

With the hinge side plumb and lightly secured, close the door and check the gap (reveal) between the door slab and the strike-side jamb. This gap should be consistent from top to bottom. Adjust the strike-side jamb using shims at the top, middle, and bottom until the reveal is even. Also, check the gap across the top of the door and between the bottom of the door and the threshold. Once all gaps are even and the door swings freely without binding, permanently secure the door frame. Drive long screws (3-inch deck screws or similar) through the hinge-side jamb behind each hinge directly into the structural framing. Then, drive finish nails through the shims on both sides of the jamb and through the top of the head jamb into the header.

Goal: Ensure the door is properly leveled, aligned, and securely fastened.