I'm lead to understand that a 'data aggregator' is responsible for maintaining the guide. I have also heard that this 3rd party will only update the guide for days well in the future, perhaps at least a week.
For live events e.g. sports, this leads to many errors in the guide.
Recording with a pvr and given the way it works with what is on the guide, one would hope that there would be an earnest desire to have the guide as up to date as possible.