When I was a young child, I remember there being a small break between the meetings. You could get up, walk around, associate, and then go back in for the second half.
At some point, they changed it to where there was just the song. And oh my, if you left, all eyes were on you. Long time for anyone, especially kids.
When was this? Mid to late 70's?
My guess is too many people were indeed leaving, and they wanted to keep them all there.