I agree. Atelier training can't give you creativity (though it
can open your eyes), and it can't take it away.
The brochure for the classical realism studio where I received instruction stated very explicity --
"The work is not creative, and it is not intended to be.
" The goal was to be able to accurately depict the subject, whatever the subject.
In a sense, we were acquiring the "vocabulary" of art, but we remained responsible for telling our own story.
The only risk to creativity, if at all, is that one's discipleship and obeisance to the training become rigid and unmindful. If your "creative" self wants to use an unorthodox composition, or adjoin non-complementary colors, or put terry tea towels and screwdrivers into a classical fruit-and-flowers scene, and you stifle that impulse merely on the basis that "That's not the way it must be done, the way it's always been done," there might be a sense in which your new skills could be seen to be holding you back, creatively. I have seen it happen, so I'm not going to say it cannot, but I think it's rare that a well-trained artist would feel constrained to use his or her skills in such service. The natural instinct seems to be otherwise. It is music theory that allows one to improvise, not the absence of it.
By the way, the fact that most examples of atelier work are characterized by a very tight finish has to do largely with the nature of the training. One would be expected not to practice piano scales with only 70 per cent accuracy. There is however, in classical realism, a strong impressionist "school," which demands no less skill in seeing your subject than does the highly finished work we're more apt to associate with the term "classical realism."
Lastly, as for measuring, it's just a tool. The coffee table built by the master woodworker is not the measuring tape or T-square he used. Some studios train you in the use of plumb lines and calipers to assist the development of your eye, and others do not permit them, insisting that they simply impede the progress and that the sooner you internalize the tools, the better. One system isn't "right," and the other "wrong." In the teaching studio, the instructor's ability to stand in the same place the student was standing and use the same measuring device (I'm thinking of a length of thread, as in the sight-size demo
(here) I put together earlier) to double-check the student's work was an efficient means of "proving" to the untrained student (often resistant to instruction -- especially if a young male!) where he or she had gone wrong.
I'll bet Tony Ryder is still able to whip out some pretty fantastic quick sketches, "despite" his skill.