Similar to the OP's routing, I just did YYZ-ICN-CGK-ICN-YYZ with KE recently. On YYZ-ICN, the routing definately took a polar route through Northern Canada, Artic Ocean and Eastern Siberia. But coming back on ICN-YYZ it was nowhere near a polar journey. We basically flew above the Korean Peninsula through the Sea of Japan, through Hokkaido then through the Pacific barely touching the airspace above the Aleutian Islands. Upon entry into North American airspace, we basically flew above the Southern Portion of the Canadian Provinces near the U.S. border then above Lake Superior & Huron before eventually reaching YYZ.