Sound is also another problem with doing a wide shot and a close-up at the same time -- just like you compromise the lighting on the close-up, you compromise the mic placement.
Generally you'd keep the two shot sizes similar if using 2-cameras in a conservative fashion, like doing a medium and close-up at the same time. It just depends on the needs of the scene. I've run two cameras on scenes with adults mixed with babies or pets, just to capture whatever unrepeatable action happens with the kid or pet on the second camera.
With action scenes, it's a little more "anything goes" although some stunts only work from certain angles, like a faked hit.