I'd never underestimate a course or reading about sailing... of course having them after sailing a lot, better if having any racing
experience listening to all that "new" nautical language.
I've sailed almost all my life from A to B, and even crewing
amateur races, and only after reading sailing books
and listening to short conferences I've realized that I knew just that, going from A to B.
After reading just one book (a good one) and listening a single
conference about trimming, my performance went up by far and the following sailing practices had a lot more meaning both racing