High ceilings are popular, but they have a downside: they are prone to get horizontal stress marks in the drywall attached to the adjoining walls. The reason is not hard to understand.
Think about a house where you enter through the front door and look upward to see the ceiling of the second story. That ceiling is at least 16-feet high. Some are 20-feet high. By code, and not so common “common sense”, the walls are supposed to be balloon-framed. This means that the studs should go from the bottom plate on the slab all the way to the top plate 20 feet up. Normal framing would have studs that go from the bottom plate to around halfway up. The second set of studs are used to get to the second-floor ceiling.
There is a reason for following the code: if two sets of studs are used, the wall will have what is effectively a hinge where they come together. The horizontal line is where the hinge is in the wall framing.