How to continually monitor in-wall moisture content?
You could contact the following EIMA, US Dept. of Energy, or Oak Ridge National combined these agencies conducted a test starting in 2005 on a building in Hollywood South Carolina and one in Washington State that lasted at least 4 years
to include test in eight climate zones.
I did the installation of the test panels on the South Carolina building.
Test panels included most exterior cladding systems.
Pick up sensors for moisture were placed on the back side of all materials used in the construction of each system
Example Exterior stucco sensor behind finish coat, sensor behind brown coat, sensor behind scratch coat, sensor behind lath, sensor behind vapor barrier and sensor behind sheathing.
Also sensor was placed in wall insulation and the back side of the drywall.
I have missed place my final report from EIMA you should be able to get info from one of the above agencies.