Here are a few examples of the point I'm trying to make about the stages using print flaws as an example.
Here's an Owen print flaws with the number of examples I found when I did the research on it.
EPDG-3.jpg
Owen.jpg
The Piedmonts were probably printed in most if not all stages that's why the % of Piedmonts with the flaw is so much lower than the EPDG's. There were a number of vertical rows (around 10-12) of the same subject on each sheet but only 1 Owen in that row would have had this flaw and it was probably only there in the one stage where the EPDG"s and Piedmont's were printed together.
Here are a pair of flaws that share similar numbers and were probably on the cards for two different stages.
SC150-649-1.jpg
Pastorius.jpg
PD150-1.jpg
Davis.jpg
Here's a thread I posted on the print flaws several years ago
https://www.net54baseball.com/showthread.php?t=215451