Some wet drywall may be evaluated for drying; other conditions may require removal. No universal stain size or elapsed time decides the outcome. Contamination, physical damage and concealed layers all matter.
Separate appearance from condition
A stain can persist after an older event, while an intact surface can conceal retained moisture. Swelling, softening or loss of integrity warrants professional evaluation. Sagging ceilings require keeping clear, not pressing the material to see whether it is firm.
Do not begin demolition to investigate
Walls and ceilings can contain wiring, plumbing and materials requiring special handling. Contamination or suspected mold can change the scope. Ask which qualified trades or specialists are needed before cutting, removing insulation or exposing a cavity.
Plan the repair sequence
Address the water source and moisture findings before closing the assembly. Ask what supports the decision to dry or replace, what cannot yet be checked and whether finishing work is included. Painting a mark is not source repair or confirmation that the wall is ready.