When does Harvard accept it's last applications?
This is my hypothesis: they're keeping some people in limbo waiting for the end of the cycle of applications. When that comes, then they will email out a bunch of KB1s to the people who haven't been held yet. But they're waiting just in case they get a bunch of 4.0/180 people before the end of the cycle.
At the same time, they are still considering people for holds that haven't gone past the 2 month wait, and it seems like the people that completed in Nov have been through the hold process. So they're probably determining hold/KB1/"unofficial hold until the cycle ends" status for people that completed after that (for the record, I URed 12/5, so I think I'm in this still-considering group).
This is all conjecture on my part, but it seems logical, especially if the submissions are fewer and weaker than in previous years. They don't want to give out KB1s to people before everyone has submitted, but they aren't going to hold them either if they think they want to give them KB1s.