At our house and many others I'm sure, the TV is on most of the day. I like the background noise and most of the time I'm not even paying attention to it. My son is 21 months old though and he'll often stand there and stare at whatever is on TV cartoons or not. Most sources say children under 2 shouldn't be watching any TV at all. My son is at the age where he's repeating everything we say including what he sees on TV so I make an effort to keep it on clean channels when it is on. Even better I put it on a music channel which plays music but shows a black screen.
I've chosen to let him watch an hour of TV a day (sometimes a little more...gimme a break, I have a 7 week old too!) His favourite shows are Yo Gabba Gabba and Rolie Polie Olie and he'll even ask for them by name. I don't want my son to become a zombie mesmerized by the TV like other people I know (who may kill me if they read this) and impede on his abilities to use his imagination and learning by play. There are too many studies out there showing how too much TV has detrimental effects on children and learning. It's just so easy to use the TV as a babysitter or in my case, to keep the toddler temporarily occupied while I'm busy with his sister. Thankfully it hasn't become too much of a battle in our house (except maybe with hubby) and my son will usually find something else to do when it's off. How much TV do your children watch?