Purpose: As responsibilities of high school principals continue to expand, their workweeks become longer, and their attention is stretched in multiple directions. How principals from various school types use their time is influenced by their organizational structures and external policies. To gain deeper insights into the workload, priorities and constraints faced by high school principals, this study examines principal time use (PTU) patterns across different school types, including traditional public schools (TPSs), charter schools, Catholic schools and non-Catholic private schools. Design/methodology/approach: Drawing on the national representative data from the High School Longitudinal Study of 2009 in the USA, this study examines and compares PTU in various leadership tasks across different school types, controlling for school and principal characteristics. Findings: Among various high school types, principals in TPS had the longest workweeks. However, the extended workweek did not necessarily result in significantly more hours or a larger proportion of their time dedicated to instructional leadership. Instead, TPS principals allocated more time to administrative tasks and student affairs than principals in other school types. Originality/value: By examining PTU of different school types, this study adds new evidence on the influence of contextual factors on leadership behavior. It also offers policy implications to enhance principals' capacities, alleviate their workload and to prioritize time use in different leadership domains.