Guy's our ARTCC admin post changes usually the same day they are recieved!! These changes come straight from the FAA and not some fly by night list.
The FAA is really slow updating their data. There are ARTCC frequencies that have been in use for years that the FAA has not updated. The AFF list supplied by the FAA has lots of omissions and errors on it. The ARTCC admin guys here do a good job keeping their list up to date but they only show the changes for a few days making it hard to track what's changed. Any reports here, from actually monitoring the frequency, would be helpful.