Cosmic variance in the volume-averaged neutral fraction ${\overline{x}}_{\mathrm{H}\mathrm{I}}$ measured in sightlines of length 100 cMpc (Δz ∼ 0.4) as a function of survey area and the true neutral fraction, ${\overline{x}}_{\mathrm{H}\mathrm{I}}$. We compare the sightline variance if the area is split between independent NIRSpec fields versus one contiguous field of the same area. Due to the large correlated ionized structures across ≳100 sq. arcmin, multiple independent fields are required to recover unbiased estimate of ${\overline{x}}_{\mathrm{H}\mathrm{I}}$.