A friend of mine once asked be if I had been given a script when I came in or if I had given everyone my script? We both laughed and said NO. There was no script. This is IMPROV!
Sorry about my extremely delayed response. Improv, indeed. I've never prepared an aikido class, ever. By time, I found a good excuse: If I prepare the class, I'm less sensitive to the needs that might appear during it.
Or I'm just lazy.