Complex infographics are effective visual formats for presenting large volumes of information in a clear and coherent manner, often integrating multiple charts, visual elements, or informational sections into a unified composition. While their structural openness allows for flexible exploration, it can also impose substantial cognitive load due to the simultaneous presentation of dense content. This study investigates how reading navigation influences cognitive load in the comprehension of complex static infographics, with a focus on deviations from the intended reading path of the designer. It also examines how specific structural features, such as spatial layout, subheadings, and font size, contribute to guiding interpretation and reducing cognitive demand. Participants viewed a series of infographic samples, identified their own reading paths, and rated the cognitive load associated with each. Based on the findings, this research proposes design principles that support effective navigation and alleviate cognitive burden in complex infographic design.