I assumed and would hope it's working real-time and is refreshed everytime you access hot on tv. It displays the programs FiOS viewers are watching the most at that given time. The parameters of which FiOS users like local or nationwide is beyond me. Lets get some real answers on this one for KJH278.
It is updated when ever they add/subtract content... it may be weekly, it may be monthly, it may not have a set schdule... keep an eye on it, if it is that important to you.