The quality often depended on the RBC for the region. Some were known for building quality and others not so much. The local cong support also helped or hindered depending on the maturity/responsiveness of the local BOE. All things considered, most passed inspection because inspectors were amazed that so much could get done in such a short time by so many unskilled workers. They allowed some to move forward when they probably should have been stopped and corrected. Doors that swung the wrong way, HVAC that did not provide adequate airflow through the building, electrical that was insufficient for the practical needs of the building, parking lots that did not drain properly, crooked walls and more.
However, most have bee remodeled and many sold. The idea was to get them done quickly to free the local cong for preaching instead of building, but they turned into PR endeavors and the problems grew exponentially. Many Brothers who were used extensively were discarded when they were unable to have high field service hours AND be at builds every other weekend.Some spent so much time away from their families that their marriages and children suffered from spiritual neglect. The fallout can still be seen now many years later.
Present day, WTC is in the selling mode, not the building mode. They can barely get the rank n' file to attend so why build more?
In retrospect, they were exciting and a trainwreck all at the same time.