What are the connotations of "me'Erev ad Boker"?
Rashi: The Kohen is obligated to place enough oil each day to burn the entire night. 1
Which they assessed as half a Log (See Ba'al ha'Turim DH "le'Ma'or Leha'alos") on the long nights of Teives and which they poured in every night, even during the short summer nights. If oil continued to burn during the day, it didn't matter. Other commentaries explain that they avoided wasting oil in this manner, by regulating the thickness of the wicks according to the length of the nights - using thinner wicks in the winter and thicker ones in the summer.