This article examines digital data use within three Australian secondary schools, drawing on in-depth interviews with 50 school staff to explore tensions between: (i) established logics of "data-driven" schooling; and (ii) emerging "datafied" practices associated with digital systems, platforms and devices. Using sociological theorisation of institutional logics, the article examines how promises of digital "dataism" are thwarted by the entrenched temporal organisation of schooling, and teacher-centred understandings of students as coerced subjects. As such, prevailing logics of state bureaucracy and professionalism combine in ways that temper the prospect of individualism, self-regulation, continuous feedback, and other implicit promises of digital data. The paper considers the extent to which school data logics can endure amid the increased digitisation of K-12 education.