I always loved Leonard's book on Mastery simply because he put the emphasis on the journey and not the destination. You are so right in that there is no end in the pursuit of excellence. Gladwell's 10,000 hours to achieve mastery of any endeavor is a pretty good rule of thumb in gaining mastery. Perhaps mastery is just a train stop on your journey. Even after reaching mastery, there's always an opportunity to expand your knowledge and skills, staying curious and open to new possibilities. What slays me is some 30 year old claiming Grand Mastery. You ain't fooling anyone but yourself.