This whole blog post is great (It’s worth reposting the whole thing).

There’s this assumption that creating a great product takes months and months of user interviews. That’s not true. But it does take a dedication to do some kind of process that results in a product. I’ve done a lot of back of the napkin usability and user experience, it always returns great results. It don’t think it matters whether you call it Lean or not.

Read on…

Any user experience designer worth their salt takes the needs of the company they're serving into account and adapts their approach accordingly – identifying the appropriate process, methods and tools to get the job done. This has been the case for as long as information architecture and interaction design have been in practice. Rigid methodology – doing the same exact thing every time despite the context – is, and has always been, bad practice.

…

(Lean’s) dictionary definition of "offering little reward, substance, or nourishment; meager" simply doesn't hold. What they are doing – which ultimately comes down to  design thinking – has tremendous reward and endless impact on the relevance of their products, the success of their companies, and the health of their egos.

…

Caring about your customers and working to make their lives better is the most honorable thing a company can do. Let's teach these companies more and better UX methods, give them ways to adapt the methods to however they work best, and encourage them to keep the needs, attitudes, and motivations of their customers at the core of everything they do.