If someone finds themselves in a situation where it's inconvenient to stop the line in order to change the string on the chronograph, they can simply note which shots are for which loads in the current string. Later, the velocities can be entered into an Excel spreadsheet and the average and std deviation can be easily calculated using the =avg and =stdev functions.
My bigger issue at my club's indoor range is that the target carrier will hit the chronograph when I change targets so I have to make the range safe anyway to manually change the target down range (though I do wait until it's convenient for the other shooters).