Redshift estimates based on the best nearest neighbour, obtained by uniformly subsampling the W1 catalogue, at fixed n_NN = 30 and Δz = 0.08. The titles of the panels refer to the surface density of spectroscopic objects of W1 used for training, with Σ referring to the complete W1 sample. Except for minor fluctuations in the redshift statistics, NezNet maintains a performance similar to the case without subsampling. The only noticeable trend is the fraction of central galaxies for which a physical pair is found, which decreases for lower densities. This could be due to the decreasing number of available training data. The percentage of real physical neighbours for a central galaxy, which decreases only slightly from Σ to Σ/8, remains around 40% and explains why NezNet is still effective.