My daughter is 4 and my son is 2. I'd very love to just grant all their request to listen to tv- We have no TV in the house so we don't have cable, we have netflix and a bunch of child's movies, on our laptop. So I'm not worried on what they listen... just how much, and how. My son sits for a half an hour and then goes off to do something else, that's very okay with me. My daugther, on the ohter hand, would stay all day in front of the laptop. Constantly asking me to put that part of that movie, then that part, then this other movie, put not that part. Moaning that this movie is too long, but still wanting to listen, but no, put that part instead.
It's very like she's tired of listening but can't stop.
So when that happens, I propose activities she likes. Sometimes she says yes, sometimes she doesn't want and keep requesting parts of movies. Sometimes I just get tired of her requests and close the computer and ask her to find something else to do.
There are days we don't go out -I'm in my first trimester afterall, I have less energy- and it really shows on her general attitude if she's listening more tv. She'd yell more, throw things, be more agressive, steal thing to her brother for the fun of hearing him yell at her...very unpleasing to everyone! A calm request for drawing can turn into a battle for which will have that princess coloring page and the blue crayon, while usually my kids play together beautifully. I propose time-in when this happens, but it does not seems enough.
Having to limit her viewing would be weird to me, but maybe she's just a little too young to really know when it's time to stop.