I believe now that the "experiences part" has more to do with with reinforcing a thought or idea of the GB than anything that happened in real life. This might not happen at every assembly but it happened to me.(30 years ago)
I think you're pretty close to the mark.
The assembly program comes to the C.O./D.O. much like a PT outline.
For the experiences part, it will read something like: "Find a qualified brother, in his 20s, ...etc, etc." Then the poor C.O. has to find someone remotely like what is stated in the outline. invariably he'll have to coerce the willing (struggling?) dupe and then at the rehearsal, both the C.O. and D.O. will be stuck with forcing the dupe to "say the right thing" i.e. spout words that are just like the outline.
Every assembly rehearsal I went to, and I went to several a year, was like that.