TSR in the three I_AB magnitude bins, used to define our slit positioning strategy: I_AB ≤ 22.5, 22.5 <I_AB ≤ 23.0, I_AB> 23.0. The magnitude bin considered is labeled atop of each bin. The red histogram shows the magnitude distribution of the targets in the total Wall parent sample. The filled green histogram shows the magnitude distribution of the targets where we could position on a slit (for both histograms the correponding number of targets is shown on the left y axis). The filled points are the TSR, which is ratio between the two histograms, with values given by the right y axis.