Door and window casings, headers, sills, and aprons run as one composition, not pieces butted together. Crown runs from a simple three-inch profile to multi-piece builds and large cove.
Inside corners are coped. Outside corners are returned. Miters are closed so the profile never breaks. Crown is scribed to the ceiling, not caulked into a gap. Paint or stain grade, as specified.
South Florida light is high, hard, and often against glass. Every joint shows. The standard is that it doesn’t.