wall-framing-takeoff counted flat ceilings but ignored the vertical face of a dropped soffit. A ceiling entry can now carry steps: [{length, drop}]. Each step is board hung in one course (ends cut at sheet length), a corner bead run along its lower edge, and a taped inside angle where it meets the higher ceiling.
One hand-counted test: a 10 ft step 12 in deep adds 10 sq ft, 10 ft of bead, 10 ft of angle and one 12 in butt joint. Not checked against a real soffit, and there is no page control yet. Estimates only, not building advice.