The "Contents of Selected Package" section of a shipment is required for our EDI implementation, and some customers require the information as well.
Since we are working with serialized items, we end up needing to select each serial number individually to put it in a package. After you've selected a split line/serial number, it doesn't disappear from the list, so it's very difficult to determine what's been selected and what hasn't. When dealing with large quantities (sometimes well over 1000 serialized items), this becomes prohibitively cumbersome.
My suggestion to make this screen workable for larger volumes of serialized items would be to make a multi-select popup, with the ability to filter the records by any field and select/deselect all records in the filtered resultset, exactly like the "ADD ORDER" button works on the Shipment Document Details.