The Theocratic Ministry School and Service meeting were two 45 minute meetings with a song/prayer on each side and a song in the middle. For that 90 minutes of program there was about 3 to 4 hours of study prep before the meeting if you looked up every scripture sited. Study prep involved getting deep into the subject matter to have well prepare, heartfelt, insightful answers during the meeting.
I have not been to a meeting since the change, but my understanding is that it is now shorter, there is little to no study prep because any answer is to be a quick reciting of the words in the source material. Other than that, most parts are prepared and presented in video format by headquarters in New York.
What used to be like attending college courses to prepare the congregation to be public ministers is now a weekly indoctrination and brainwashing. Leave your brain at home. Watchtower will do all the thinking for you.