We do not limit but our kids seem to monitor themselves with their screen time. Some days they are all about it, some days they could care less and are interested in anything but the glowing screen, just out being boys. They rarely stay doing one thing for an extended period of time when its computer/game/tv involved...the newness of whatever they've found wears off and off they go to something else one of the other children are doing.
I've seen strict regulation of TV end up badly in the young adult years when the parents no longer have rein....on the flip side I've seen kids get addicted to the glowing screen as well from overuse and continue that behavior into adulthood...I think that is more to do with types of personality than anything, some people have a more addictive type personality than others and it shows up in many ways. Its a parental choice, and what you think is best for your kids, as you know them best sorta answer.
