I am against throwing darts in the cockpit during cruise flight.
We agree with the cabin staff on how we fly through the night. Some captains want them to check on us every 30 mins, by calling (which wakes everyone up) or by waving into the camera, which we will answer with clicking the doorlock...
Or we call the cabin staff every 45 mins and if we don't they'll call us...
This gives us the option that one takes a short nap (20-30 mins). I napped several times on board, it really helps making the flight safer.
I see no need in both pilots checking their instruments every 20 seconds over the atlantic ocean at night, better be awake during the approach.