||With the aim to test the categorical formulation of a spatial concept on the functional, desirable characteristics of land-use distributions inside periurban landscapes, in the research we envisaged and developed an original quantitative method, deployed in nine study-cases worldwide. Increasingly facing a generic set of pressures from suburbanization and unregulated land-use change, unwanted spatial outcomes in those landscapes often arise after trespassing critical thresholds of ecosystems’ processes inadvertently: Overriding the minimum-area requirements, for example, of crucial ecosystems providing basic ecological services to whole urban regions. Spatial concepts can be powerful tools for strategic planning of territorial systems, helping to avoid shortsighted plans and policies. From the narrative of a spatial concept supportive of strategic planning and regulatory policies for territorial sustainability (the “Aggregates-with-Outliers” -AWO), we developed an original synthetic, quantitative method fostering statistical analysis between diverse locales, years, and scales -as well desirable scenarios. From the joint maximization of size variance and land-use diversity (JMV+D model), we evidenced deficits and potentials on the composition of heterogeneous periurban landscapes, from the universal perspective of the concept. It is considered a tool (among the many required) for the strategic planning of territorial sustainability in those landscapes, especially required of a flexible definition on the desirable spatial outcomes of plans and policies.