You do understand at least intuitively that it's not even mathematically possible - let alone practically - to train 100 percent of teachers to be in the top 10 percent of teachers, right? The definition of "good" and "gifted" is only used relative to an average. No amount of training can make the average teacher better than the average teacher; it's a logical impossibility, and misunderstands the central effect of training and the goal of the person being trained. No student nor teacher cares about be trained to some objective standard of competence. Rather, the goal is to be better than one's peers and you can't have all teachers be better than all teachers unless you reject the concept of teachers being comparable.