A comprehensive investigation of the Fermi surface topologies of a series of Cr1-xVx and Cr1-xMox alloys highlights the role of nesting in determining the periods of the oscillatory exchange coupling observed in multilayer systems. The long-standing controversy over the origin of the long-period oscillations across Cr and Cr-based alloys is resolved, with the evolution of one dimension of the N-hole ellipsoid Fermi surface sheet being directly associated with the evolution of the period.