Resonant energy transfer in molecular systems can remain efficient under substantial environmental dephasing, making transport enhancement alone an insufficient indicator of persistent quantum coherence. A central question is whether the environmental scale governing the disappearance of coherence-sensitive behaviour coincides with the scale governing the loss of resonance-enhanced transfer. This work develops an open quantum-system framework for examining that separation in a weakly driven donor-bridge-acceptor molecular network. The model incorporates coherent intermolecular coupling, external resonant excitation, population relaxation, pure dephasing and irreversible acceptor trapping. Transfer efficiency, time-averaged quantum coherence and resonance enhancement are evaluated systematically as functions of environmental dephasing. The numerical analysis identifies two distinct operational scales. The selected coherence threshold occurs at Γ_coh=0.1431J whereas the resonance-survival threshold occurs at Γ_res=1.5294J. Their difference, ΔΓ_RC=1.3863J, defines a finite resonance-coherence separation regime in which resonance-enhanced molecular energy transfer persists after the selected coherence measure has fallen below its operational threshold. In the baseline model, the resonance-survival scale is approximately 10.7 times the corresponding coherence threshold. These results demonstrate that resonance survival and coherence survival need not occur on the same environmental scale. The framework provides a quantitative method for separating persistent resonance-mediated transport from the persistence of measurable quantum coherence and may be applicable to excitonic, vibrational, photochemical and externally driven molecular networks.
