In art and photography, the rule of thirds is applied to composition. To build interesting composition think of the picture as overlaid with a grid of three lines across and down. Place your subject or focal point off centre on one of these lines instead of dead centre. Pay attention to the horizon in the following pictures.
In painting and photography, I struggled with this concept. I want to be fair and symmetrical, so I tend to cut things in half. However, if I follow the rule of thirds, I like my art better.
The same can be said for writing. A three act structure is not symmetrical. It is really three quarters. The first quarter is the first part. The second in the middle two quarters and the third is the last quarter, but we think of it as thirds.
In the same way, I want to give each character equal space in the story, but that does not make for interesting stories.
While patterns are appealing, there are times when they become boring. Playing around with composition in photography, I want to keep thinking about ways to apply the rule of thirds to literary works. Not necessarily to make it a habit, but to make it more natural and engaging.