After identifying the value stream for a product, the focus is on avoiding batch and queue between different steps in the process flow.
You must ensure that the next downstream operation has:

• only what is needed
• just when it is needed
• in the exact amount needed

Enabling flow without interruption, detours, backflows, waiting and scrap presents a constant challenge.
General, the batch size should be reduced to the smallest possible size.
The end target is to enable single or one piece flow, meaning producing only one product at a time.

You can learn more about one piece flow and lean manufacturing at http://www.LeanManufacturingCoaching.com