How the cross-correlation detection strength, 𝒮, varies across time resolution and SYSREM iterations for four hypothetical cases averaged across 100 realisations of the same observing night. (i) Top left: reference case of a hypothetical observation (R = 100 000) based on fiducial planet WASP-127 b. (ii) Top right: scenario where the reference case’s planetary signal strength is halved. (iii) Bottom left: scenario where the reference case's transit duration is halved. (iv) Bottom right: scenario where the reference case is observed with half the spectral resolution (R = 50 000). In these plots, a large number of short exposures corresponds to a lower S/N_exp (bottom of vertical axis) and a small number of long exposures corresponds to a higher S/N_exp (top of vertical axis).