What are the advantages and disadvantages of the devil’s advocate, dialectical inquiry, and consensus approaches to making strategic choices?

Review The Secret Origins of Corporate Strategy at https://www.youtube.com/watch?v=DQVf7984YDA.  What is Walter Keiechel’s view on the value of business consultants?  Do you agree?  Using the materials in the text, what are the advantages and disadvantages of the devil’s advocate, dialectical inquiry, and consensus approaches to making strategic choices?