Update: Wolf2191 has corrected the absence of a Wikipedia entry for Rav Yeshayah Berlin that I had lamented in note 4.
Update II: I recently encountered a transcript of a speech by Rav Aharon Kotler, in which he takes for granted that Ya’akov’s meticulousness has aspects “that are not found in the שלחן ערוך ” and in which an employee is not obligated. As we have seen, this is the position of Rav Yeshayah Berlin, in contradistinction to that of Rav Ahai and Neziv: