It’s waves. Each house has a wave. You must shoot all shots, as well as the shot that represents that house. So that shot is needed twice.
Then the battering ram is lit for a super. Hit that to end the wave, add a ball, and start the next wave.
Rinse and repeat until all houses have been completed.
Then victory laps start where it’s just hit lit shots until you drain.
If you drain during Iron Throne, and have balls left to play, Iron Throne will continue. You can also play it with one ball, so don’t think it’s over if you drain down to one ball.