Lifesaver,
You are correct...there are several chapters that hold "concurrent" rituals, especially for large Associate Member classes. I don't agree with running an initiation that way, but, I can understand the reasoning behind it.
The largest class I ever watched go through ritual was 28
- and, as you can imagine, it took a very very very long time.
I won't go into specifics, (neither should anyone else) - but suffice it to say, the larger the class, the less sleep anyone will get.