• Postponing the routing decision to the shop floor, i.e. to dispatching, may have a favourable effect on waiting times, by grouping the machines of work centre 1 in a single capacity group and collecting jobs in a common queue for both machines. This prevents jobs from waiting on a machine, while the other is idle. In fact, reducing the sources of variability, due to machines sharing of a common buffer reduces the total amount of buffering required to achieve a given level of performance. This is known as a form of pooling that involves sharing inventory buffers to cover variability in multiple sources of demand. Jobs are selected to be processed on machines, accordingly a first-in-first-out (FIFO) rule.