Sheetrocking & taping companies hire sanders to sand out houses.
The people doing the sanding have never taped or painted so how do they know when they have done a good job.
OR if there is a problem how to fit it then and there so there is no time lost.
The average age of the sanders is 19 years old most of them kids.
They love to use sanding sticks (sanding pad on the end of a 5′ long stick) they cannot touch or see their work and all their work has been sanded with 100 grit sandpaper leaving sanding groves in their departure.
But they are the one doing the finish job before the painter comes in. They leave groves and miss some areas.
The best way to sand is to hand sand both with a sanding pad made by 3M (fine) and 2 hand sanders.
When sanding use a 150 grid sandpaper over the entire surface and use a 300-400 grid sandpaper to remove the sanding marks left by the 150 grid sand paper.