In the supplied two-dimensional, compressible, single-fluid resistive-MHD island-coalescence model, with uniform magnetic diffusivity eta, fixed initial state and boundaries, the normalized inverse-resistivity control is S_eta=1/eta. For mesh-qualified, pre-plasmoid cases with S_eta in [250,4000], the flux-window-averaged reconnection rate R has a log-slope in the band [-0.55,-0.45]. For a declared contrast Sa<Sb, p_eff=[ln R(Sb)-ln R(Sa)]/[ln Sb-ln Sa] must lie in that band after accounting for numerical uncertainty. Define R=(0.05-0.01)/(t(psi_rec=0.05)-t(psi_rec=0.01)) using the same initial-state-subtracted reconnected flux and normalization for both cases. The exponent may vary between contrasts: this hypothesis does not require an exact global power law or posit a probability distribution for exponents. A qualified contrast with its numerical-uncertainty interval wholly outside the band is a counterexample. Test this claim and, if it fails, investigate a minimal explanatory repair with a prediction challenged by fresh simulations.