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In addition to adding complexity to a model in stages, models that have a broad scope are sometimes easier to build in phases where additional sections are added incrementally to the model. This method of "eating the elephant one bite at a time" allows a portion of the model to be built, tested and debugged before adding new sections and makes a large task more manageable.
For unusually large models, it may be useful to identify definable boundaries within a model to permit model partitioning. Model partitioning is the process of subdividing a model into two or more modules that represent physically separate sections within the system. The purpose of model partitioning is to allow model sections to be built and debugged, possibly even by separate individuals, independently of each other. Once sections are finished, they can be merged together to create the overall model. This "divide-and-conquer" method of model building can greatly reduce the time and difficulty in building and debugging large models.