Predefined shapes are a useful tool in landscape design as they offer a structured approach to the design process. These shapes can be used to create a variety of elements such as garden beds, pathways, and water features. By using predefined shapes, the designer can ensure that the elements of the landscape are symmetrical and balanced. These shapes can also be used to create a sense of flow and movement within the landscape, guiding the eye from one element to the next. Additionally, predefined shapes can be used to create a theme within the landscape, such as a formal or contemporary design. Overall, predefined shapes offer a quick and easy way to create a cohesive and visually appealing landscape design.