Quote Originally Posted by Kibbick
...but as she asymptotically approaches ‘perfect’ there is less and less that needs to be done about training her, and she meanwhile spends more and more time thinking of and acting for him. It appears to me that this would result in an unbalanced, non-reciprocal relationship, where he is more important to her than she is to him. Does this happen? Why or why not? What can or should one do about it?
It does not happen. I would assume that a master with a slave approaching excellence in her training (since perfection is obviously impossible) would actually be more and more interested in:

expanding her limits
enjoyng the fruits of said training
nurturing his prized posession
showing her off
giving her that which motivates her. (love, attention, sex, pain, humilliation, etc)

Besides, a slave that feels neglected by her master will probably rebel in some way, therefore regaining her master's attention. (Even if it comes in the form of punishment)
As a submissive, I am far from being well trained, but my relationship with my partner is such that we see no end to the learning and growing that is still in our future.