By having more than one model, you gain a greater understanding of the problem space and the behavior of the system. Easterbrook, et al. Heitmeyer, et al. However, time must be spent keeping all of the models synchronized with each other and the system implementation. If all of the models overlap in a large portion of the problem, making one change in the system implementation can require updating all of the models.
Building models elicits questions to be posed to domain experts.
This gap in the model helped to formulate important questions to be asked of domain experts. The use of monitored and controlled variables in the SCR tool set forced the author to critically examine the level of abstraction in the model. It takes time and effort to learn a new tool and to learn the syntax of a new modeling language. See Appendix C for a breakdown of the author's time. Seven percent of the effort was spent modeling in the SMV tool.