School improvement frameworks and their associated reform efforts often have limited durability and are frequently not fully implemented. Improving their viability, requires a more realistic understanding of contextual organisational structures and the school culture in which the reform is to be implemented. Internationally, and in Australia specifically, education research has informed policy heavily promoting collaboration as a school improvement strategy, with the aim of building teacher capability and student achievement. Consequently, secondary school leaders are charged with promoting the need for teachers to collaborate meaningfully with hundreds of students, carers, parents and colleagues each week across the ‘silos’ of subject departments and grade levels in their school. Social Brain Theory suggests that there are cognitive limits on the number of natural face-to-face social interactions that one can have and maintain. Relationships require significant investment in time and frequency. Additionally, sociality is much more cognitively demanding than at first thought, having unforeseen influence on improvement efforts. The number of interactions required in a collaborative environment, an individual’s likely cognitive overload and the ‘silo’ nature of the school’s organisational structure must all be considered. This paper offers an alternative theoretical framework to support policy makers and leaders in optimising school improvement efforts.