What a moisture reading actually means
Almost every argument about whether a drying job was finished properly comes down to a disagreement about what "dry" meant. There is a defensible answer, and it is not a feeling or a number of days.
The dry reference
Wood, drywall and concrete all carry moisture normally, and how much is normal depends on the material, the building and the season. So a reading in isolation means very little. What means something is a comparison: the same material, in the same building, somewhere the water never reached.
That unaffected spot is the reference. The wet area is dried until it matches it. Stopping earlier leaves moisture in the assembly; continuing past it accomplishes nothing and bills for equipment that has finished its work.
Why the surface lies, and lies more here
A meter placed on a surface reads the surface. Drywall dries from the face inward, so the paper can be at reference while the gypsum behind it and the framing behind that are still well above it. Carpet dries long before its pad does. A hardwood floor can feel fine on top and hold moisture in the subfloor underneath.
On this coast the gap between how a surface feels and what the assembly holds is wider than usual, because the air is doing less of the work. In Manhattan Beach or Redondo in June, an overnight marine layer keeps indoor humidity high enough that material gives up moisture slowly all night and then feels convincingly dry by afternoon. In Simi Valley the same assembly would be genuinely finished.
What a proper record looks like
Readings taken at the same locations each day, with the locations described well enough that someone else could find them. The reference reading recorded alongside them. The date and the time, because morning and afternoon are not the same measurement here. And a final set showing the wet area matching the reference before anything is closed up.
That record is worth more than the equipment. It is the evidence that the assembly was dry when the wall went back, and it is what gets produced months later if growth appears in the same place.
Different materials have different acceptable ranges, and a reading that is appropriate for framing is not appropriate for finished flooring. The point of the reference is that it removes the need to argue about which number is right.