Don't think of it as drywall pantyhose for the ducts.
The issue is getting the lumber hook up to the ceiling joists without wasting too much precious inches of width or height, and then making sure they are all square & level.
If there are too many jigs and jogs it looks amateurish to me.
I think I know what you mean. Too many changes in heights or widths = weird. I'm just trying to keep things efficient in size since that duct in the first picture is very low, Barely 6 feet from floor to soffit.
Maybe it's because I'm exhausted. I've been pushing hard in the past week on this project since my family&kids are out of the country until next week. Well, actually it's more like the window closes on Wednesday night as I go to China to joint them on Thursday morning.
Tomorrow is a fresh day. I'll start up with coffee