The only point that can be added here, in relation to these two examples, is that point of grading for each book is over a decade between each of them.
CGC is like any environment, with continued learning, different graders, changes in personnel, market conditions, heck...even new glasses for some (myself included ). It all creates variables from one passage of time to the next.
It'd be interesting to see early SA issues graded at the same time for those .2 grade differences. Not for the point of second guessing the process, but illustrating the differences that create the increments. This something that is rarely seen, and properly understood. Particularly in the SA, with 40-50 year old books.
Grading modern books at CGC has to be the easy gig in comparison