Is there a reason why there's sometimes multiple "Bag 1" bags in particular sets?
I assume this is down to purely logistic reasons, like the available plastic bag sizes, the characteristics of the different packaging pipelines (it is known that LEGO takes extreme care when packing the bags with pieces, including multiple weighings to ensure not a single part is missing - the precision required to check for the presence a small element could preclude the range necessary for bags containing many and larger pieces), the locations of the different packaging facilities, and so on.