HSS peak velocity as a function of the CH area. Panel a: red and green ovals divide our CH sample into two different groups. Panel b: fits for the different CH groups. The blue line shows the linear fit applied to the whole sample, while the red line is the linear fit applied for the subset that provided the highest cc. The gray dotted line separates the two groups and it sets the threshold beyond which the HSS peak velocity does not increase with an increasing CH area. The light green line corresponds to a power-exponential fit for all points and confirms the physical threshold in velocities.