My IDC (if you want to call it that) was about 6 months long. We learned to teach by actually teaching real students. At the end of that time 3 of us took the 4 day instructor exam. Everyone had a different style, different lectures, and taught skills in different orders according to the experience we had up until that point with actual students.
We all came out of it with instructor cards. We all met the standards and passed the exams. Our OW portion was done in a 55 degree quarry in the rain with about 10 ft of vis. It was a blast. My two "students" for the OW guided dive portion were an instructor with about 20 years teaching and an instructor trainer with 25 or so I think. They were intentionally a hot mess as divers and buddies. It was blast!
We all came out of it with instructor cards. We all met the standards and passed the exams. Our OW portion was done in a 55 degree quarry in the rain with about 10 ft of vis. It was a blast. My two "students" for the OW guided dive portion were an instructor with about 20 years teaching and an instructor trainer with 25 or so I think. They were intentionally a hot mess as divers and buddies. It was blast!