Transit timing residuals for the planets of our sample. The open circles mark the data compiled in Maciejewski et al. (2018, 2020). Open squares are the new literature mid-points redetermined in this study (for Kelt-16 b and WASP-103 b). The filled dots are the new determinations reported in this paper: the green and blue points come from TESS and ground-based photometry, respectively. The uncertainties of the refined ephemerides are illustrated with bunches of 100 lines, each drawn from the Markov chains.