Wiggly ray effect: Mean fractional reduction of the comoving distance r(s) reached after travelling a comoving distance s. The x-axis indicates the redshift instead of s for better readability. Dots indicate directional averages in the simulation ⟨r(s)⟩_d; the dashed and solid lines respectively indicate the theoretical predictions of Eqs. (68) and (69). Error bars are computed following Appendix D.2.