A through through is a type of shot that has no effect on the stones in the house or on the sheet. In a throw through, the thrower will deliberately throw the stone with a heavy weight so it goes through the house. Essentially, a skip wants the house to remain clear, so the stone will be intentionally thrown out-of-play.
Purpose of Throw Throughs
Towards the end of a game of curling, one team may be winning by a few points. Thus, the team that is currently winning just needs to remove enough opponent stones so that the opponent is mathematically eliminated from winning. However, cluttering the house with stones increases the chances of the opponent scoring. Thus, it makes more sense to throw a stone through the house to prevent stones from cluttering.
IMPORTANT: Throw throughs will only happen if the entire playing area is clear of stones, or if only one other stone is present. If there are more guards or stones in the house, a takeout, peel, or tick shot will be played.
Although throw throughs usually occur with the lead's stones, a skip may decide to throw through one of their stones, but this occurs in very rare instances. This can happen if many stones are in-play, and there is no possible way that any more points can be scored in the end.
Throw Through Split Times
When performing a throw through, you need to throw the stone with board weight (or sometimes a little heavier). As we have learned with board weight, an appropriate split time from the backline to hog line is about two seconds. Since curlers usually give the stone an extra push when they release it, it's pointless to learn the split time between the two hog lines. Long story short, make sure that the stone has enough weight similar to that of a heavy upweight shot.