Probably the best visual I’ve seen describing what Lean UX can be, and what it is not.
When you add a legitimate use-experience phase to your process, it will, by nature, be perceived as something of a bottleneck. UX is in place to help refine requirements and define interaction, naturally adding more time and effort to the product definition and engineering phases.
But at it’s highest level of maturity, user experience is a function of product development, not web development, and Lean UX gets it right in that regard. Many Silicon Valley startups are still hammering the square peg of Agile into the round hole of UX, and it just doesn’t work.
At the end of the day, the product-development process is linear. You can’t and shouldn’t start building something without having some idea of its scope, its breadth. But by using Lean UX, you can deliberately enter a project with collaboration baked in, something that happens in many organizations but rarely as a philosophy or codified process. If you’re going to build a new product, best to marry your busy and user goals as soon as possible.