On what surface? Are they just framed in but not covered yet? I thought the skim coat was the surface added to sheet-rock to cover seams. Then a texture is added to that. Am I missing something?

If you mean Plaster Vs. Sheetrock, sheetrock is better, faster and cost effective. Doing plaster is time consuming, it's a big mess and today you will probably pay an arm and a leg and that is if you find someone who still does that.