There is an urgent need in the acute health system to use resources as efficiently as possible. One such group of resources are operating theatres, which have an important impact on patient flow through a hospital. Data-driven insights into the use of operating theatres can suggest improvements to minimise wastage and improve theatre availability. In this paper, a short extract of surgical data from participating Queensland public hospitals was statistically analysed to examine the effects of session type, session specialty, scheduling the longest case first and day of the week on theatre utilisation. It was found that day-long sessions (as opposed to separate morning or afternoon sessions), mid-week sessions, certain specialties (eg. neurosurgery sessions) and not doing the longest case first were most beneficial to theatre utilisation. Awareness of these findings is important in any redesign activity aimed at improving flow performance.