Zack needs to know

I need some input from someone familiar with the news media industry. Fox19 is proclaiming itself to be "the most powerful name in primetime news" in the city, based on it having the highest ratings in the city for primetime news.

Here's my question: isn't primetime considered 8-11 p.m.? If that's the case, wouldn't Fox19 be the only network that has their nightly news in primetime (CW 25 doesn't count, it's not a major network)? If so, it's just another example of how networks make claims that don't actually mean anything.