The five whys are also described in John Rossman's, The Amazon Way: 14 Leadership Principles Behind the World's Most Disruptive Company. I reviewed that, back in 2016: Part 1, Part 2, Part 3. The five whys were covered in part 3/principle 12. Another relevant principle from that book is: "Have a Bias for Action", which is principle 8, covered in Part 2.