Related for Beitzah 37:9

Said Rabbi Shimon ben Elazar, Beit Shammai and Beit Hillel did not disagree on whether the burnt offerings that are brought daily [to the Temple] should only be brought from non-consecrated [animals], nor on whether [with respect to] peace offerings that are brought on the other days of the year (i.e., other than Festival days), that if one wants to rely upon [animals from] tithes, he may so rely. What they disagreed on was in regards to the Festival offerings [brought on] a Yom Tov itself. For Beit Shammai said, all of these must be brought from non-consecrated [animals], and Beit Hillel said, one brings an obligatory offering from non-consecrated [animals], but [thereafter] if he wants to rely upon tithes, he may so rely, and on the other days of the year, he brings obligatory offerings from non-consecrated [animals].

Rabban Shimon b. Gamliel says: The house of Shammai used to say that a priest because of his Heave no immerse on public holiday bath. But he may go into immerse when he passes from one purpose to another and from one group to another. What does it mean "when he passes over from one purpose to another"? If he wants to use his dough on his press or use his press for his dough, he immerses on the same day.