Transit timing residuals (O-C diagram) for WASP-19 b under different data inclusion scenarios. Each panel compares linear (solid black), quadratic (dashed green), and cubic (dotted brown) ephemeris models fitted to subsets of the data, with and without the inclusion of TESS transit timings. The top row shows results using all data, while the middle and bottom rows show fits restricted to the best 20%, 30%, and 40% of light curves based on photometric precision. Literature data are shown in red, Danish light curves (DK154) in blue, and TESS data in purple.