There are a few factors for the circular pan. The first one manufacturing & material seem to hold the most weight.
Manufacturing & Material
Circular pans boost significantly greater manufacturing efficiency. It is easier to manufacture a circular pan from sheet metal by forming process. Compared to a square or rectangular pan with sharp corners, circular shapes experience less stress during forming, reducing the risk of cracks or tears. Circular geometry is well suited for automated manufacturing processes, less complex tooling, and reduced material usage, these translate to lower production costs. Additionally, their shape facilitates easier storage and stacking, saving space and reducing handling challenges.
Heat Distribution
Circular pans excel in heat distribution due to their inherent geometry. The round shape aligns naturally with heat sources like flames, promoting even radiation across the entire surface. Furthermore, the circular design fosters better convection currents within the pan, enhancing heat circulation and ensuring consistent cooking.
Functionality
Stirring and flipping food in circular pans is a breeze, making them ideal for tasks like sautéing, scrambling eggs, and omelets. Their curved sides eliminate corners, maximizing the cooking surface and allowing you to prepare larger quantities compared to square or rectangular alternatives.