Station ID is every hour. Also you have to say it in a very specific format: Call letters, city; or call letters, frequency, city. No additional words in between: “WKRP in Cincinnati” would be invalid.
TV stations are allowed to do it visually. When I was young it was common to see it as a full screen ID in between shows (often with a quick weather report, “time and temperature”). Later most stations I saw quit that and just put it as a bug at the bottom of the screen over top of the show.
Including your frequency is especially effective for customer retention - I still remember the MW frequency of one of my favorite radio stations from my youth because it was included in the name, even though I listened to it via satellite ("Virgin 1215" - apparently it's called Absolute Radio now, and medium wave transmissions were discontinued on 20 January 2023: https://en.wikipedia.org/wiki/Absolute_Radio).
TV stations are allowed to do it visually. When I was young it was common to see it as a full screen ID in between shows (often with a quick weather report, “time and temperature”). Later most stations I saw quit that and just put it as a bug at the bottom of the screen over top of the show.