Top left: distribution in count rate of point-like sources characterised in the time domain. Red: EXTraS/STV analysis. Blue: 3XMM; the total source sample is shadowed. Top right: same as top left, EXTraS/STV vs. 4XMM. Bottom left: distribution in count rate of point-like sources displaying variability. Red: EXTraS/STV analysis (p-value p < 10⁻⁵, according to results of the fit of a constant model on 500 s or optimal time bin, or with more than one Bayesian block in the sensitive segmentation). Green: EXTraS/STV analysis, based on uniform bin light curves only. Blue: 3XMM timing analysis (p-value p < 10⁻⁵, according to results of the fit of a constant model). Bottom right: same as bottom left, EXTraS/STV vs. 4XMM. In all panels, all bar items start from the baseline.