Median and 68% confidence interval of the differential contribution to the total characteristic strain signal, based on 2000 Universe realizations, shown across MBHB log₁₀-chirp mass bins for both circular and eccentric populations. We compare the results at two observer frequencies: 3.1 nHz (left panel) and 27.6 nHz (right panel). Vertical lines represent the median chirp mass value at which the cumulative contribution (integrating from lower masses) reaches 10% of the total strain signal for the circular (solid line) and eccentric (dashed line) populations.