Time is essence in all processes involved while providing customer service. Very often the duration of a specific service is regulated by the law. However, it is also affected by other external and internal factors. Quantitative approaches to model the service time and creating systems that support the workflow management process are vital. This paper proposes a model of business process analysis on the operational level for various service-oriented organizations (including governmental agencies). The model estimates time of rendering services for heavily regulated public organizations. The analysis of the obtained results is discussed, potential applications are identified, and future research directions are formulated.