Breaking waste into categories does have many benefits. First of all, they provide a way of organizing your mind when you evaluate a process to identify its wasteful activities. Before I review an operation, I always look at a list of the categories of waste. It keeps my mind sharp and open to the different ways waste creeps into a process.
Categories of waste are also useful when it comes time to make improvements. For example, all of the transportation waste you identified may be fixed with a redesign of a work cell’s layout. All the inventory waste may be eliminated by putting kanban in place.
The reason I say that the categories of waste don’t matter, though, is that people get wrapped up on trying to identify precisely which category of waste something falls into. A pallet of parts on the ground is a waste of inventory. But it also adds the waste of transportation to get to the far side, and possibly a waste of waiting when a forklift comes in to move around the pallets.
In some cases, I’ve seen people get into heated debates over which category of waste a particular activity should fall into. The ironic part…it is a very wasteful way to approach waste reduction.
The key is just to identify that something is waste. Don’t worry about getting the category of waste absolutely right, because eventually, all of the wastes you identify should end up in the same category…‘eliminated’.