Why was Karna a one day warrior in Mahabharat?

Why was Karna a one day warrior in Mahabharat? Karna fought in the Kurukshetra war for seven days and performed well in most of those days he participated in the destructive war. Karna countered a group attack the five Kekaya brothers who fought for the Pandava side on his first day in the Kurukshetra war (11th day) and there is no mention of any defeat he suffered on that day. On the 12th day, Karna countered a group attack of Bhima, Satyaki and Dhristadyumna. He also resisted Arjuna for some time before eventually succumbing to Satyaki in a fierce battle which marked the end of battle for that day from both the sides. Karna suffered a number of defeats on both the 13th day (at Abhimanyu's hands in archery fights) and the 14th day but performed relatively better on the 14th day. Karna suffered five consecutive defeats at Bhima's hands on the 14th day but eventually had the last laugh by capturing the Pandava brother alive and sparing his life in the sixth encounter on that day. Karna defeated Bhima fairly and squarely on the 15th day since he had the experience of fighting with the Pandava brother on the previous day. Karna defeated Nakula and a group attack of all the Pandava warriors (except Arjuna) on the 16th day so he also performed well on that day. Karna was invincible in all the encounters on the 17th day (except one battle with Bhima and final encounter with Arjuna) therefore it can be ascertained that he was never a one day warrior since he performed well in most of the days he fought for the Kourava side.