How a vendor may prioritize shipping.

Since I am verboten from posting in a certain thread and there is a lot of speculation about this topic, I'll share what I have seen done in other market areas.
Merge it, delete it, whatever is appropriate.

For example, on a large bulk sale, eg, UHQR KoB, it would be efficient to coordinate with the shipper. The shipper may request to be given in bulk all packages with zip codes associated with one of their distribution centers. That way there is much less handling. The shipper can load the material right onto a truck/plane going to that center rather than having to sort thru a random geographic batch and process each package indivually.

That is why the shipping notices may appear to be random rather than in Order No. sequence. They likely started with over seas orders, then will work there way down from the largest geographic batches to the smallest. If in a large city, good for you, Hicksville, might be a bit longer.

Just conjecture, but shipping is a well established logistical science whose aim is to minimize cost, maximize profit and move stuff the most efficient manner for the sender and receiver.