Achieving optimal operation is a fundamental objective in most production and service systems. The core of this pursuit involves seeking the minimum or maximum values of one or more target functions within specific constraints. For instance, it is common to strive for the minimization of operating costs, lead times, and resource utilization, or the maximization of revenue and coverage. These objectives must be balanced against a range of factors, including market constraints, resource capacities, budgets, and technological conditions. A significant challenge in the quest for optimal operation is the quality and documentation of data. Often, data are neither clean nor well-documented, which complicates the process of finding and implementing optimal operational strategies. This paper focuses on the human element in decision-making processes, acknowledging the limitations inherent in human capabilities when making decisions. The primary aim of this paper is to present a case study that highlights the constraints of human decision-making processes. Through this case study, we examine the impact of human factors on achieving optimal operation in production and service systems. The study provides insights into how human limitations can affect the decision-making process, particularly in the context of imperfect data and the complex interplay of various operational constraints.