LARA:

The hollow terra cotta blocks were generally a commercial construction
material. Commercial compared to Residential. Sometimes the materials
that are really designed for one type of construction would over lap
into the other due to the architect or contractor moving into a project
outside of their normal field. Sometimes it was just someone trying to
be innovative. I assume the collection of structures was a single
development and the similar materials were not due to package built
homes.

Bryan