At the end of Yerushalmi Sukkah, there is a puzzling Gemara. There is a discussion regarding the 24 watches of Kohanim. Every week, the work in the Beit HaMikdash was taken care of by one watch. The watch of Bilgah is treated negatively, for reasons stated in the Gemara. The question arises, why not mix Bilgah in with another watch? And then it is asked, why not just eliminate the watch altogether and leave it with just 23 watches?
We can't do that, as it is written "They were established by David and Shmuel the seer, with their faith" (Divrei HaYamim 1 chapter 9) Great skill (a slight change to the word for faith) is here, that one watch does not take and take again from the Ancestral Field until the others take. Rebbi Abahu said: I calculated them and one watch does not take and take again from the Ancestral Field until the others take.