Thanks for that article, Jay !
That information will not ensure a coil set up correctly. It needs calibrated on a coil testing unit to produce a smooth running engine. Articles like this one is why so many give up and convert to something else for ignition.
Perhaps the author could have also included setting by musical note or length of spark - equally comparable to the methods described.
"rough and ready adjustment" says it all.
I can imagine all the multiple sparking and wildly varying coil currents.
Rather like most of the coils I get given to rebuild...
I've just done a set where the upper cushion springs had been glued shut. Pity, because they were new contacts.