Initially, it may not be possible to assign all the people needed exclusively to a value stream. There may be some individuals working in more than one value stream. The cost of these shared workers can be assigned to individual value streams in proportion to the time spent in each stream. It is also true that even in the most ideal of circumstances, there will be some individuals who will remain outside any particular value stream (the plant manager, for example) However, with multiple value streams, the unassigned costs are likely to be a very small percentage of the total costs. Finally, in reality, having a value stream for every product is not practical. The usual practice is to organize value streams around a family of products.