I guess I wasn't very clear. My apologies, and I will try again.
George is an instructor. He uses his favorite methodologies to teach a course. It takes him 16 hours of instructional time. He decides that he wants to teach more, using the same methodologies. He adds 4 hours to the course, and is thus able to add 4 more hours worth of instructional content. (That is consistent with your statement.)
Sally is an instructor. She employs different methodologies. Because her methodologies are more efficient than George's, she has been teaching George's 20 hour class all along, completing it in 14 hours.
Bob is an Instructor. He employs similar instructional methods as Sally. He targets those people who do not desire to learn the minimum requirements, but attain a higher competency. He teaches a longer program which is 60 hours in length.
What I'm disagreeing with here is that longer training equates to less efficient instruction. Without knowing the facts it's arrogant to make such a presumption.