Accretionary wedges are the prime locations of exhumed high-pressure (HP) and low-temperature (LT) metamorphic rocks. Previous tectonic models invoked the corner flow theory with a premise of slab-parallel motion to explain the upward return flow of buried metasediments. In this study, we develop a generalized corner flow model with additional kinematic and rheological factors and evaluate the limiting conditions in which a wedge can set in significant return flows.