1. A method, comprising: one or more computers performing the following actions, wherein the one or more computers each comprise at least a processor and a memory: detecting a given shipment event for which one of a plurality of shipping methods is to be selected; determining a current output state of a discrete event model representative of shipping method selections for one or more previous shipment events; and in response to detecting said given shipment event, for each of the given shipment event and one or more pending shipment events that occur subsequent to the given shipment event, producing a selection of a corresponding one of said plurality of shipping methods such that the selections of shipping methods for the given shipment event and the one or more pending shipment events collectively mathematically optimize an objective function, such that producing the selection for the given shipment event depends on both the given shipment event and the one or more pending shipment events; wherein said objective function is dependent on respective costs of shipping associated with said given shipment event and said one or more pending shipment events, and is further dependent on a weighted deviation between said current output state of said discrete event model and a target output state of said discrete event model; and wherein the one or more pending shipment events correspond to one or more shipments that have not yet been presented for shipment labeling.