Bob: Yes, wood studs are becoming a rarity in comm work, and some resi is going steel also.
As to the holes......that was a decent explanation, and I've been around a while, & can't say I ever came across that clamp in any old resi with lathe & plaster walls/ceilings. Usually it was/is old black steel gems, ears turned back & 1/2" wood screws into the lathe. Or really old pancakes with a gas pipe hickey ane at least four BX's.
