Prep
Patching, sanding, stain-blocking, and caulking are labor. A room with sound walls needs light prep; a room with damage needs significant work. Prep is the biggest variable and the biggest value — it is what makes the finish last.
Coats
A same-color refresh often takes one or two coats. A dark-to-light change or deep accent color needs a primer plus extra finish coats. Each additional coat adds material and labor time.
Access
Vaulted ceilings, stairways, and furnished rooms require ladders, scaffolding, and careful protection — all of which add labor. Empty rooms with standard ceilings are the most efficient to paint.