@stassit We have a 9 year old and limit his TV to 24 minutes (one episode of whatever he's watching) during school. He only watches after we do all of our other work together: homework (which he's fairly independent), piano practice, extra math (multiplication and division facts via gamified flash card), dinner, chores (help clean the table, prepare bag for the next day, just small stuff), and independent reading (10 minutes minimum). We then read again before bed.
After everything he totally deserves to zombify in front of the TV for a few minutes. We also try to explain the reasoning behind TV being the exception and not the rule--sometimes we don't always get TV and it's ok.
During the summer we do the same stuff together, minus the homework, and heavier on the math and reading. He can watch TV lots during the summer in the evening. I admit we sometimes just need a little downtime as parents and if the Simpsons raised me, they ... D'oh.
Our one year old gets 0 TV and won't get TV for many years time.
Our 9 year old talks about how his friends "use" TV and he clearly understands that it isn't a healthy habit. Regardless, he's still a kid and would easily sit for hours if unsupervised.