Various predictions of the coupling model (CM) are known to be in agreement with observations of relaxation phenomena in polymers. However, as shown herein, when applied to the terminal relaxation, the model deviates from experimental data for monodisperse polymers; to wit the shape of the terminal relaxation spectrum does not conform to the CM equation. Nevertheless, the main premise of the model-that the dynamics transition from intermolecularly uncorrelated to entanglement-coupled relaxation at a temperature-independent crossover time-is supported by the data. Specifically, it is shown that the continuity condition of the model, relating the magnitudes of the non-cooperative and cooperative relaxation times, can be determined numerically to yield predictions for the molecular weight and temperature dependencies of the terminal viscosity in agreement with experiment. Previously the derivation of this continuity relation relied on the assumption of a specific form for the relaxation function＇s shape.The discrepancy concerning the shape of the relaxation function is apparently due to alleviation of the entanglement constraints, with consequent time-dependence of the coupling parameter. Previously, the coupling parameter has been regarded as strictly constant; however, at times approaching and longer than the terminal relaxation time, mitigation of the lateral constraints causes a decrease in the degree of intermolecular cooperativity, and hence in the coupling strength. The deviation of experimental spectra from the model＇s prediction is likely due to the neglect of this fluctuation in the severity of entanglements.