Results of our multi-Gaussian fitting for the TNG50 (orange), FIRE-2 (dark red), and MeerKAT (blue) galaxies. Top panels: Fraction of spectra modelled with N components (1​ ≤ ​N​ ≤ ​5). Bottom panels: Median value of the distribution of the Gaussian standard deviations computed for all line profiles modelled with N components, as a function of N. The different panels show our results for spaxels in different ranges of (inclination-corrected) H I column density, indicated at the top of each panel. The dashed and dotted curves in the leftmost panels show, respectively, the regular and irregular populations of simulated galaxies.