Dan,
I basically agree with Tom Doak on his answer, and points 1, 2 and the PS. I rarely do planting plans, although, on my recent trip to Vegas for GIS, I had a chance to go by one of the few courses I did plant from scratch - Stallion Mountain - and was quite pleased with the overall results 18 years of maturing later. Looked pretty much like I imagined, although even leaving spaces between my clumps of trees, they grew together more and visually more from the tee vantages than I thought, slightly erasing the open clumps feel I imagined.......
That said, an LA degree is, IMHO, the best basic training, but I didn't really know anything about gca until working a few years for Killian and Nugent. I suspect the same is true for almost anyone in the biz, that they had some kind of mentor that really taught them routing, grading for golf, construction, etc. etc. etc.