Great question, as I've been wondering myself how bad off we are!!!
We are also in the "terrible parents" camp. We never had a set limit on it for dd. She would get a show at breakfast so DH could tend to the animals and maybe another one at night before dinner. But since DS arrived, she's had WAY more than she should. It's been hard to pull back, but DH and I keep saying that we need to put a limit for her. I would like to shoot for an hour a day knowing that in school days she gets none, usually. And on days when DH is home alone with both LOs (2 days a week) she is getting more. As someone else said, it's the only thing that keeps her quiet, although she's gotten better about playing alone lately.
Curious to read what others post.