In my last several posts, I've been harping on the value of looking at flow and not worrying (much) about whether it's in a push or pull context.  Either way...you gotta have flow.

In my last post, I put forth a simple "value stream" scenario that illustrated the typical barriers to flow.  As I pointed out, you couldn't tell from the description, whether it was set up as push or pull but it was clear there was no flow.

I think the lean literature leads us astray on this matter.  This leading astray might not be intentional but it's easy to get the impression that implementing pull is all about kanban cards, small batches, and manufacturing cells.  Change the layout of the equipment, make up some kanban cards, and - voila! - you've got pull.  But, as I say so often about most aspects of agile manufacturing, it it were that easy, everybody would be doing it.

Let me be clear: I'm definitely not opposed to cells or kanbans and such.  It's just that they don't work that well until you've got flow.  And the folks who've made pull systems work understand this.  In fact, one of the arguments made in favor of pull is that it forces  the organization to improve flow.  Pull without flow is worse than push without flow because the poop hits the fan quicker and causes more problems, in the short term, when it does.