Decline in disk fraction, f_disk, with disk age. Blue lines show the disk fraction considering disk dispersal when losing 90% (light), 95% (medium), and 99% (dark) of the initial mass. The red points correspond to the observed disk fractions of nearby clusters within 200 pc, and the dashed line is the fit exponential decay, f(t) = exp(−t/τ), yielding τ = 7 Myr from Pfalzner et al. (2022). The yellow points are from Fedele et al. (2010), giving τ = 3 Myr. The top and bottom panels correspond to disks with viscosity ranges of 10⁻⁵ ≤ α ≤ 10⁻² and 10⁻⁴ ≤ α ≤ 10⁻², respectively. The χ² values are shown in the bottom left of each figure.