Having the 3rd party external factor is critical. Walking the halls and open door policy is minimum expectations for any leader trying to stay in the loop. The problem is it is too easy for people to "be on their best behavior" no matter how hard you try.
Great leaders need to provide a source for ideas and expression in internal blogs, with external consultants and more. And, a culture where mistakes are looked at as learning experiences for everyone. loosen up be real and and encourage others to be themselves.