Detections (blue) and non-detections (orange) of Na I doublet lines using high-resolution spectrographs based on projected spin-orbit angles (λ) of the system. The green point is the position of WASP-31 b found using our observed values for λ. The top panel shows the (non-)detections with respect to V magnitude. The bottom panel shows the (non-)detections with respect to T_eff of the host star. Data were extracted on 7 March, 2025. Although sodium detections exist spanning vastly different orbital alignments, non-detections show a clear preference for aligned systems (1st and 3rd quadrants); however, given the small number of non-detection publications and the higher chance of close-in giants being aligned, we cannot distinguish them from observational bias.