I spent 4 years getting a B.S. in chemistry and 6 years getting a Ph.D. in biochemistry. I subsequently learned "pharmacokinetics", my specialty and my bread-and-butter for the next 27 years, in 8 days! Granted, I had a good foundation to build on before the final "8 days", but the point is, I agree with you that most courses (just like most books) could be wrapped up in about 10% of the time they actually take. I guess the rest of the time is spent just growing up.