Krisos 25a: They said of Bava ben Buta that he used to bring an asham taluy every day, except for the day after Yom Kippur. He said, “I swear by the Temple that if they would let me, I would bring it then too. But they say to me: wait until there is a possibility that you sinned.”

כריתות כה ע”א אמרו עליו על בבא בן בוטא שהיה מתנדב אשם תלוי בכל יום, חוץ מאחר יום כיפורים יום אחד, אמר: המעון הזה, אילו היו מניחין לי הייתי מביא, אלא אומרים לי המתין עד שתכנס לבית הספקֹ.

The desk of the Rogachover Gaon was always piled high with postcards, on which he would write his responsa. As soon as he finished writing a postcard, he would ask his shamash to go and drop it in the mailbox, because he didn’t want to make the asker wait any extra time to receive his answer. 

Rabbi Pinchas Teitz said of the Rogachover, “He wrote so many responsa, I would estimate between forty and fifty thousand. He remembered every letter he wrote – the asker, the question, the date and his response. I am not sure if there was anyone in Jewish history who wrote as many responsa as he did.

“One day, so many letters arrived that the mailman could not fit them all into the Rogachover’s mailbox, so he placed them on the doorstep. When I came to the house, I picked up the bundle and saw that there were 16 letters and 6 double postcards. The Rogachover sat down immediately and in about an hour and a half, all his responses were written and ready to send. He did not even have to look up anything in a sefer.

“Often he began his letters with a question or chiddush he was reminded of as he marked the date. For example, he once penned a letter on the day after Yom Kippur. As he wrote the date, “Erev Shabbos Kodesh 11 Tishrei,” before he wrote the year, he mentioned the argument of the kohanim to Bava ben Buta that he should not bring an asham that day, because there was not yet a possibility that he had sinned. Then he was evidently bothered: why is it not possible? In reply, he referenced the Gemara in Me’ilah 14a-b. There the Mishnah states that if the treasurer of the Beis Hamikdash buys wood for building, and someone sits on the woodpile, he commits me’ilah – misuse of sacred property. But, asks the Gemara, didn’t Shmuel say, “We build the Beis Hamikdash out of non-consecrated materials and then later we consecrate the finished building, lest one come to derive benefit from the materials during the building process.” Rav Papa resolves this by saying that the Mishnah is talking about wood that is needed for that very same day. Such wood is, in fact, consecrated before the building, because in one day, there is no need to worry that one might sin.

Source: Rabbi Pinchas Teitz, writing in the introduction to Tzofnas Paneach, referring to responsum 124; the Rogachover by Yair Borochov.