School principals are agents of change in the implementation of education policies as they oversee accountability actions that serve to monitor and evaluate student achievement and identify the measures required. In Québec, where "results-based management" (RBM) is encouraged, the "professional learning community" (PLC) approach ensures this accountability by enabling members to gather, manage, and analyze student data. This case study pertains to the experience of one principal who sought training on how to integrate a PLC in his school. In the context of RBM, characterized by an increase in administrative tasks, this principal ultimately experienced a low sense of effectiveness regarding his supervision practices by having few legal structures to support this supervision. Two series of teaching activities are proposed related to prioritization tasks and the role of PLCs in a context of work intensification and RBM.