Back in the 1960's, when I first started attending the KH, it was pretty standard for congregations to have the Sunday meeting at 3:00, with a 15 minute intermission between the Public Talk and Watchtower Study. That, of course, was when they were still trying to get the public to their Public Talks. The theory was that a lot of people who were religious might not be willing to give up their own church service to attend a talk at the KH, so it was held at a time when they would not have to choose between the two. At least that's the way it was explained to me. Back then, there was also no prayer or song before the Public Talk, since they didn't want the people who came to hear a "free lecture" to feel as if they were required to join in our worship. The WT Study was opened and closed with a song and prayer.