I rent a two-room apartment. The ceiling and top wall in the living room and kitchen were pale yellow because the previous tenant was a serious smoker (about 2 packs a day I think). When she moved in 2019 I dyed my hair. But I wasn't on the surface. I tried and gave up, raise your hand and sand the height and the ceiling, it hurt. And they called professional painters, they have an estimate of $1200 to $1500 because the smoke is yellow. So I made it myself, just painted and coated. It wasn't bad, but with a delay of about 6 months, the yellow color appeared on the surface. He's kind of ugly, at least little yellow spots on the surface. So it needs to be sanded and then stained. I learned the name "drywall sander" from a colleague. I don't know how many square feet, the living room and kitchen ceiling, the short hallway and all the walls I sanded with this sander in 2 hours, plus about 20 minutes to sand the edge and corner by hand. I'm not a pro, I work slowly and carefully not to sand too deep, I don't want to sand drywall paper. It comes with a vacuum cleaner to suck up the dust, but covering it is always better. More importantly, my shoulders don't hurt. A PLUS.