Protect what is not being painted
Floors, fixed furniture, hardware and adjacent finishes are named in the protection plan because paint control begins before a container is opened.
Repair and adhesion come before color
Loose material, contamination, glossy existing coatings, patches and stains each need a different preparation decision. A finish coat does not make those conditions disappear.
The surface and use decide the finish
A ceiling, wall, door and built-in do not receive the same wear or cleaning. Color and sheen are selected together with the substrate and how the element is used.