One of the ways to improve energy efficiency in transportation is through efforts aimed at increasing the usage of public transportation by residents. This, in turn, is closely related to residents’ preferences. One of the most frequently cited factors influencing the attractiveness and quality of public transportation is the frequency of connections. This is important not only for urban transport but also regional transport, which has significantly lower passenger flows. This paper aims to present how the frequency of connections affects the attractiveness of regional transport. An original method for determining the attractiveness of public transport, based on the share of adult, senior, and youth passengers with single tickets and monthly passes, is introduced. The results of research on the structure of passengers and flows to/from the district center are presented. Based on the research results, attractiveness factors are calculated for each town. The statistical analysis clearly indicates there is a strong correlation between the attractiveness of regional transport and the frequency of connections (Rs = 0.807, p = 0.001). Moreover, for every connection increase, the number of adult passengers will increase by an average of 1.5. Assuming that these additional passengers switch from individual to public transportation, the resulting reduction in energy consumption due to an increase of one connection is 0.33–0.69 kWh for each kilometer traveled by these passengers.

Service frequency is one of the key determinants of public transport attractiveness, yet empirical standards for regional bus services remain poorly defined. This study examines the relationship between the number of daily bus service pairs and regional public transport use using data from Poland and two Czech regions (the Plzeň Region and the Vysočina Region). Public transport use was analysed separately for adults and for children and young people using two original indicators. For adults, the logistic model provided the best fit, revealing a clear saturation effect. Despite substantial differences in the overall level of public transport use, the characteristic service frequency thresholds were remarkably similar across all analysed regions. The identified thresholds corresponded to approximately 4, 8, 12, and 20 daily bus service pairs and formed the basis for a five-level classification of regional bus service standards. For children and young people, the relationship was weaker, and no single functional form clearly outperformed the others. The proposed framework contributes to sustainable regional mobility by linking service provision with observed passenger use and by providing evidence-based reference levels for planning and evaluating regional bus services. The identified thresholds may support the development of evidence-based service standards that improve accessibility and avoid inefficient service provision, providing a practical basis for balancing passenger benefits and the efficient use of public transport resources.