It is a well established research conclusi0n that humans suffer from something called “confirmation bias”. That is, we tend to believe what confirms our beliefs and disregard what challenges them. Rita Gunther McGrath points out that you find a corollary in organizational leadership. As a result, it is a good idea (especially when competitive advantage cannot be sustained) to institutionalize ways to find and consider evidence that contradicts the assumptions behind the current business model.
How? Well, a charismatic CEO might be able to get this information if he or she is looking for it. Or an independent review group set up for that purpose might work. Or one might bring in outside experts. Or one might find ways of building new sorts of internal networks. Or some combination.
The message, however, is that assumptions need to be tested and it that testing will not happen automatically. And instituting a process of testing is a leadership challenge.