In the design of fiber links for both continental and transoceanic optical communication systems, the optimization of span length is of high importance from both performance and cost perspectives. In this work, the maximization of signal-to-noise ratio (SNR) is investigated by optimizing the span length in wideband (up to 4.5-THz) Nyquist-spaced optical fiber communication systems. A simple and accurate closed-form expression of the optimal span length is provided, and a quick estimation of SNR is also described for practically feasible and cost-effective span length values.