In the field of model-based development, and especially model-based systems engineering, the efficient and effective use of system models and specific models is of great interest. However, models strongly depend on the method they are linked to. Methods require models as input and associated models that are part of the method itself. Subsequent, methods are applied to adapt, enhance or generate output models. If a model is analyzed regarding its fidelity, level of detail, or maturity, only a combined consideration of methods and models in the development approach leads to a valid assessment. Therefore, the principle link of methods, system models, and specific models is defined and a concept for the application in product development is presented. It is stated, that a combined view on methods and models leads to improved accuracy of information interpretation and therefore optimizes efficiency and effectiveness during the product development.