I recently received an email from a guy challenging the legitimacy of organizing into value streams and lean accounting. The linchpin of his argument: "I can't find anything saying Toyota has done any of that". This seems to be a fairly common view - something of a Toyota acid test for all things lean. Of course, at the same time the most common arguement offered up in resistance to lean is, "We're different - we aren't like Toyota."
Seems to me if we want to get all Toyota-y about things we have to take Shingo's words to heart when he wrote, "We have to grasp not only the Know-How but also Know-Why."
Most plants are very much unlike Toyota plants, because making cars has some very unique characteristics - like one value stream per plant. That's the nature of the auto industry. It's tough enough to make one type of car, let alone making a bunch of them. When the auto companies make more than one model under one roof, even Toyota can only do it when the cars are very similar. They don't make full size pick-ups and small sedans on the same lines, or even in the same plant.
Most manufacturers make something with a lot fewer parts than cars; and they make more than one product type - hence the need for value streams. An auto plant basically has one big value stream map, and all of the costs in the plant are incurred somewhere along that map. Most plants - with multiple value streams - have a trickier challenge with costs: To figure out which value streams go with which costs.
In fact, there are a lot of things that are easier in a Toyota plant than in most plants - kanbans, for instance, and heijunka. When everything in the plant is flowing to one place - one assembly point - these tools are a whole lot simpler than when they can flow to multiple points with differing demand volumes and rates of demand variability. Doesn't mean the underlying principles don't apply - Shingo's "Know Why" - but it does mean the math and application techniques have to be different.
I wouldn't dream of taking anything away from Toyota. Making cars is tough, and them conjuring up the principles of lean changed the world. That said, however, using Toyota as the acid test for whether something is lean or not is rather naive and intellectually lazy.
In most companies and most plants, asking 'what would Toyota do?' is the appropriate question - not 'what did Toyota do?' And when you head down that path, you inevitably get to things like value stream organizational structures, lean accounting and a whole lot of other managerial and shop floor techniques that you won't find in a Toyota plant.