Results of the robustness tests for WFI2033−4723 time-delay measurements presented in Sect. 3.4. The shaded vertical bands correspond to our fiducial results, labelled “PyCS-mult” and “PyCS – WFI” in Figs. 3 and 4 for the top and bottom groups of panels, respectively. The values indicated above each measurement represent the 50th, 10th and 840th percentiles of the respective probability distributions.