So, maybe it's not a full month. Then again, I'm not really back. I am writing this in an Internet cafe in Ho Chi Minh City, Vietnam.
If you want to study one-piece-flow, and want to see why moving small batches around is better than lugging large ones, HCMC is the perfect place. The streets here have more traffic than anything I've ever seen. There are very few traffic lights, and driving on the right side of the road is sort of a very loose agreement. Also, the most common vehicles are scooters and light motorcycles. There are 30 million scooters in Vietnam, and by the look of it, most of them drive by my hotel each day. (I'll upload some pictures when I get back.) One would expect the result to be total chaos and confusion. It isn't!
Actually, the traffic flows like nothing you've ever seen (unless you've been here, of course). There are two reasons for this. The first is that though the streets are packed with vehicles, each vehicle is small and manouverable. The second reason is that the drivers drive very softly. They look ahead, and when they see any tendency to congestion they just slow down, or speed up, a bit, and steers gently to one side. The traffic flow rarely stops. There are two main causes of congestion: cars and tourists. Neither is nimble enough to move with the flow of the traffic.
You might think this has got nothing to do with software development, but it does. Speaking in general terms, the streets of HCMC are a business system, and the vehicles are goal units. In Gothenburg, where I live (well, the city closest to where I live), there are traffic lights in every street corner. Those lights regulate the traffic flow by creating batches of vehicles. The result is that when there are a lot of cars in the streets, queues build up. In contrast, here in HCMC, the traffic moves all the time. There are comparatively few queues.
In Theory Of Constraints terminology, there is little build-up of inventory in the HCMC traffic system. Value is added all the time (i.e. the vehicles are moving closer to their destination all the time). In agile development terms, the HCMC traffic flow with small vehicles and no traffic lights corresponds to using small stories instead of large use cases, and short iterations instead of long ones.
What it comes down to, is that it is all about the flow, always.