Decisions about whether to approve fossil fuel projects have major implications for climate change, biodiversity, and Indigenous rights. In Canada, cumulative effects tend to be only weakly assessed, with each project reviewed on its own terms. This paper investigates how fossil fuel companies strategically define project boundaries to facilitate resource extraction. Drawing on a preliminary scan of applications to Canadian federal review bodies from 2010 to 2022, complemented by detailed document analysis of three selected cases, we ask: in what ways have oil and gas proponents actively constructed scale through their project plans – with what consequences for regulatory scrutiny? Through careful reading of project applications, hearing documents, and company websites, we identify three strategies: (1) splitting work on the same infrastructure into multiple applications; (2) incrementally expanding a network; and (3) portraying interdependent facilities as stand-alone projects. These tactics are within the law, yet they narrow the scope of issues that regulators assess and make it more onerous for affected communities to participate in multiple reviews. Case studies of the Line 9 pipeline, BC Pipeline network, and Gazoduq/Énergie Saguenay facilities show how regulators exempted smaller projects from more rigorous assessment, deemed cumulative effects assessment unnecessary, and excluded broader issues such as climate change and successive encroachment on Indigenous lands. Our findings contribute to work on the material consequences of relational scale, decolonial critiques of Canada's environmental governance regime, and efforts to advance climate justice by articulating how the legal geographies of energy projects shape responsibility for climate action.