As a professional it is invaluable for me to realize that I am only as good as the tools I possess. If I stop growing and learning I am doing a disservice to my clients. Science is an ever changing arena - in my profession I study the science of human health; eating, fitness (mental, spiritual, physical) and relationships. What I learn today will be expanded on tomorrow. I feel that I am not able to point my clients in the right direction if I have not glimpsed down that path myself. I can not say that I am fully evolved and have all the answers, nobody does. If I am working with a client that has outgrown my ability it is my responsibility to that client to refer them to a practitioner who will be able to take them further.
A perfect example of this has been seen in many a yoga class...the teacher comes in every week and teaches the same class, the students who attend regularly are able to move through the class by memory and may even be able to recite verbatim the teachers description of poses. Now, this class may be a brilliant class, but as you continue to practice you should continue to grow - if you never press beyond your limits and find a new edge you stop growing and get comfortable.
The best way to handle this would be either for the teacher to recommend these students move up to a higher level class, or, if this is a multilevel class the teacher should incorporate more change and challenge to classes.
Once we stop learning we stop growing, in every day of life there is an opportunity for growth, it is our choice whether we acknowledge these opportunities or let them pass us by. I have chosen to never stop learning and look for the opportunity in all that I do.