This paper engages, Sara Ahmed's theorising on 'the uses of use' to frame an analysis of the hidden, embedded effects of standardised testing policy that have become normative practice/s in Queensland, Australia. It (re)examines data from an ethno-case study into the datafication of assessment and learning over one school year, in primary and secondary schooling contexts, to understand the uses of the National Assessment Program -- Literacy and Numeracy (NAPLAN) in a new, critical light. We explore schools' contemporary uses of NAPLAN -- intended or otherwise -- to demonstrate how the policy effects of NAPLAN have become insidiously submerged within the daily practices in schools. Drawing on interviews with 27 teachers and seven school leaders, classroom and staff meeting observations, and artefact data, we reveal the invisible yet profoundly altering presence of NAPLAN and its consequences. Specifically, we analyse the ways in which NAPLAN practices, structures and technologies are both hidden and yet manifestly altering as a) practices that disappear into their uses, becoming unidentifiable and routine; and b) practices that follow well-used pathways that further embed particular uses. We counter rhetoric of NAPLAN normativity and complacency, instead demonstrating that its current uses, while not originally intended, are insidious and profound.