I don't know that all important things are done at the annual meeting - they sneak stuff in any where they can.
Doctrinal changes are often just published in the WT as a matter of fact - they expect people to just nod their head in agreement and move on.
They make announcements at summer conventions. I would think something at a circuit assembly would be local news and/or procedural rather than anything else. And, they are tying in more and more people together through video feeds.....So, really it could be anything.
And what constitutes "big news" in JW Land is really not that consequential in real life, so there's THAT.