Fraction of unobservable galaxies and pairs of galaxies in the VIPERS parent catalogue as a function of the number of targeting runs N_runs. Points show the case when multiple survey realisations are generated only spatially moving the spectroscopic mask, while lines result from also rotating the parent catalogue by θ_Rot. For the latter case, vertical dashed lines delimit the subset of targeting runs sharing the same θ_Rot. Blue filled points and continuous line show the fraction of unobservable galaxy-galaxy pairs while red empty markers and dashed line correspond to individual galaxies.