I wish I could magically transport folks reading this particular thread to the places I work in Japan to watch some folks I know there working. The core level of just "throwing skills" (not dealing with astehtices yet.... just forming....to start with copying a specific form) that is expected out of an apprentice put most in the Western world to shame.
Training there is typically very different from that what we do here in America. Most Americans would simply not DO it. They would quit in frustration (many do). Generalizing is always wrong, but here in America we tend to be in a rush to be "creative".... and that frequently gets in the way of developing good core material handling skills. In Japan usually the core handling skills are honed to a mastery level before the "creative" side is ever let loose.
Typically a new apprencice starts with either a small plate form (small pickle type plate) or a small cup form (a yunomi). These are thrown off the hump. LITERALLY thousands of these are thrown before the person is allowed to move on to another form. Even in their "free time usually). The standards of matching to the original are painfully precise... right down to weighing the trimmed finished forms. The learning days are long and hard ............and in the winter....cold, and in the summer ..... hot.
Usually there is not much tollerance for "almost" pieces. It is the Yoda approach...... "Do or do not, there is no try". I've regularly seen the master potter at a number of places pick out one cup from about 50-60 sitting there as an apprentice is working and say something like ... this one is OK...... recialm the rest and make more.
That one piece is usually picked out and set next to the model form that will be in front of the apprentice... and the apprentice is usually then left to figure out themselves WHY that piece was picked above all the others that were there. That sometimes difficult and long term introspection goes a long way in the development of the skills and particularly the EYE of the apprentice.
Once the apprentice can throw this first single piece they are studying to the high standards... they move on to the next simple form. The complexity of the forms and the scale sloowly is increased over time.
Many of the 2nd and 3rd year apprentices at the pottery I work at a lot in Japan typically are throwing 300 - 400 yunomi cups in a day. The next day or the day after they trim them all in a day. These are matching in form just about like mold produced, including the precise dimensions of the foot, and the total weight and balance.
It is completely HUMBLING....and I've been doing this professionally for 44+ years.
Professor of Ceramics; New Hampshire Insitute of Art
Guest Professor, Wuxi Institute of Arts and Science, Yixing, China
Former President and Past President; Potters Council