I can't seem to grasp what you are getting at...
"Can we enforce the strict rule of the existing numbering sequence, or can we change them in this one, that will be "modified" so that all of the numbers beginning with 1 through 21 will be on the left, and 22 through 42 on the right?"
Some mfg have a printed directory label/card that is 'odd-even', others 1-42 in a vertical format, some provide a blank lined card with no numbers, some provide 'stick-on' numbers, and there are probably a few other variations.
As an EC, I'mm from the 'odd-left' school, and yes, it's a routine that has taken me a while to 'break', especially after I turned off the incorrect breaker that WAS properly marked on a 'left-right' format.
As an AHJ...it must be marked, and correct.
As to logic of the format....I have no Article to cite. Perhaps UL or NEMA can address and correct this???