I used to limit the amount of TV my kids watched, but don't anymore.
My girls are 7 & 4. For a week straight, they watched TV all day. And then the novelty wore off.
For example today - they got up, had breakfast, painted, did a sewing activity, got dressed, colored, played the keyboard, watched 2 shows on PBS, had lunch, played badminton, and are now watching a VHS tape.
Granted its hot out today (in the 100s) so we are inside more. But once fall and winter hit, we will be outside more often and less TV gets watched.
TV is a good resource for learning - especially for my oldest whom is a visual learner. I don't limit the books they read, the toys they play with or tv they watch.
But I'm not the usual I suppose. I also let my kids pig out of junk food one day - they've never done it again because they know it hurt their stomachs.
Just my 2 cents,