It's skilled software architecture. Some layerings of the problem into decomposable pieces allow for less communications and some layerings of the problem requ

It's skilled software architecture. Some layerings of the problem into decomposable pieces allow for less communications and some layerings of the problem require more communication. The emergent but desirable property of more parallelizable is dependent on details that are small and subtle. Project management cannot possible guarantee this. The outcome of the architecture, how much do people need to communicate, is an input to the project management.