Hi Craig,
Thanks heaps for the discussion. Don't bust your balls in getting an answer back, currently the messaging is running fine in production, the small batches are not causing a huge issue other than causing more rows being added that are necessary.
It's mainly, if I see something that doesn't look right, even when things look like they are operating fine, I investigate further rather than leaving it.
I'm going to take my sanitised script and see if I can't create the same behaviour I'm seeing in production.