We can not manage the number of shipments the supplier uses to delivers goods (that's the main reason to not create a supplier shipments by default). Indeed in case we agreed to have several orders we should always encode the last one as delivery date because it's when we agree to have all the ordered quantity.

The problem is with current behaviour we lose the information if the supplier is still on time or not.
As far as the delivery date is still in the future the system should consider that the goods will be on time (because we do not have any information on the delays).