JC
Any gca should probably work as an apprentice in whatever office they can get into, just to see how its done, and at least visit a course under construction - right now, that's probably the biggest access problem anyone could have!
And yes, you are correct hole concepts should probably be studied at their point of origin, leaving the CBM hole to study somewhere between the 4th and the 6th at Mid Ocean. That said, NGLA is worthy of study anyway, but you have to know what you are looking at.
That comment reminds me of the old joke about the monks hand copying bibles when one realizes that its possible that they are just copying some old mistake, rather than the original. One monk goes to the vault containing their original version and comes up sobbing uncontrollably a few weeks later. When asked why he is so sad, he replies, "The right word is "Celebrate!"".