In addition, Lean puts emphasis on isolating variables but I don't see enough about the use of judgement. Instead I read how we should pursue it like a scientific experiment. But what does that mean? In a scientific experiment you are anal about every little variable and constant. Last time I tried to do that while practicing Lean it ended up being the opposite of Lean.
This is more a criticism of how Lean is positioned to new people than the method itself. Most studies I see are not people who are following the specific Lean philosophy but kind of naturally developed their own. Most failures I see are guys finding it difficult to employ judgement after reading Eric's book. I think he can do a better job of explaining nuances and exercising judgement when doing Lean.