yekke please tell us where in the gemara it says they must be changed.
A similar question is what it says in Menachos 89, 1, it must have a half-lug, the amount to stay lit from night to morning. According to the Beis Yosef (670) in the first answer that they split the oil into 8 portions, or even according to the Pri Chadash there and Tosafos Harash that it was originally filled entirely and every day an eighth burned, this is not being done. Even though according to the Tosafos Harash this law only applies when possible, we know the famous question, if ???? ????? ????? why did Hashem need to do the ness with the oil? The Sfas Emes answers ??? ????? ????? ?? ?????, ????”? ??? ??????? ???? ??? ?? ?????? ????? ??????. Hashem cherishes his people and their mitzvas, so he did this miracle so they would be able to perform the mitzva, when they looked for the opportunity to be mehader and do the mitzva of lighting the menorah by searching for oil. Based on this even according to the Tosafos Harash his answer is problematic, Hashem would likely arrange for the miracle to fulfill the mitzva in the most mehudar way.
-Lubavitcher Rebbe