How long does a child play video games on a school night

It all depends on the games and the child. Generally, for some casual games like stuff on the iPad or downloaded from an apps store, you'll be looking at about 1-2 hours. For hardcore older console games, depending on the amount of dedication you could be looking at about 1-4 hours, possibly even all afternoon if allowed. It also depends on the child's attention span, because a more attentive child will spend almost twice as much time on a game, as a rough estimate.