The AstraZeneca plant model was not my project either. It came from another team and needed me to help modify the model. The model itself already existed. It was provided by the scheme design company and was already quite detailed, but the model needed to be updated according to the modifications made during the construction drawing phase. At first, I only took over the main units, but later all of them were handed over to me, including requirements for the model from the management company.
The main facade slab uses the "Assemblies" function, which I rarely use in Revit.