Final answer:
Repetition is the design element that can be easily created and applied to assist a designer with maintaining consistency in page layouts.
Step-by-step explanation:
The design element that may be created one time and easily applied to assist a designer with maintaining consistency with important elements within page layouts is repetition. Repetition involves using a unifying feature, such as a pattern, that is used more than once in how elements like text features, typeface, or color are used on a page. It helps to create emphasis, explore a theme, and ensure consistency in a design composition.