No, this is not good wire that could be reused. It is old, black, fabric-wrapped wire that has been there many years. The light fixtures that he is putting in the out-buildings are mostly LED. Double whammy - low cost to run and low heat output to help prevent fires.
When my DH was in high school, he helped his Dad's best friend wire a garage. The guy was a Master Electrician and he liked the kid, so he taught him how to do it right. DH is a civil engineer now, so everything he does is done right or not done at all. He hates to have to redo and fix stuff.
That plywood may not be defective, just not smart and on the laaaaazy side! Maybe that's why it was sold....couldn't be trained.
I hope you have a drywall lift.