Consultants tend to over-rationalize what they see around them. For example, they visit a very successful company and then begin to think that company is successful thanks to to the way it does things. They tend not to consider that the studied company may be successful in spite of many of their practices and behaviors. The consultant then falls in love with their mental schemes and tries to preach these "success secrets" to other companies. By the time others begin to listen to him, the original studied company is not very successful anymore and the consultant thus ends up preaching from a vacuum. So, what makes a company successful in the first place? Let's start by underlining that luck plays a part. However, as Jim Collins states: luck exists but it cannot be a consistent strategy. Also, let's stress that companies are unique and what works on one might not work at all in another one. Thus there is not even such thing as a "great leader.