Boundary between the contact-developing and the contact-avoiding models for different initial donor masses (from top to bottom, 10, 30, and 100 M_⊙) assuming the ejected material carries the specific orbital angular momentum of the accretor (i.e. α = η = 0, β = −ε, B = 1). The colours indicate the assumed mass-transfer efficiency. The dashed lines show the boundary of L₂ overflow, and the dotted lines represent the critical mass ratio for dynamical timescale mass transfer derived from Ge et al. (2010, 2015, 2020).