Although I've never witnessed this error on my account (boy, that would have been a terrible experience by what you've read!), I had unanswered questions about bandwidth since the very first few days I joined.
So, thanks for this post, really great research on your part! I upvoted and re-steemed (I'm not in the position to deplete my bandwidth with these actions, lol).
It would still be interesting to know what's the rate at which bandwidth regenerates every day.