Being a good leader means constantly toeing the line between being consistent and being adaptive. If you fail to be consistent, no one will ever believe in you or believe that your vision is honest. At the same time, you must acknowledge when things are not working and when the world had changed around you and be willing to change with it. It is a fine balancing act that must be performed if you want to succeed in the long run.
Consistency builds authenticity, but staying ahead of and leading change is where true leadership happens.