Zimmerman is correct in saying that a seven-day wait after any bleeding has become standard practice, almost never dispensed with. However, she gives the incorrect impression that the seven-day wait after a menstrual period of three or more days was a formal enactment of Rabbi Yehudah Hanasi, and that the so-called “ḥumra of Rabbi Zeira” refers only to the extension of this rule to a one or two-day menstrual period. This description, based on BT Nidah 66b, leaves out the essential information that Rabbi Yehudah Hanasi’s enactment referred only to women from the countryside (basadot), that is, to those who had no recourse to rabbinic consultation with regard to distinctions between bleeding that is part of the menstrual cycle–which, on the basis of scriptural law, would not require a wait of seven blood-free days—and “irregular” bleeding. The Babylonian women of Rabbi Zeira’s time took this practice upon themselves despite the presence of rabbis among them, and extended it to include bleeding of one or two days’ duration as well. Thus, for contemporary women in the era of advanced communications technology, it may be said that all aspects of this practice are based on a ḥumra introduced by the Babylonian women. The practice of waiting seven blood-free days following the end of a regular menstrual period is variously described in the Talmud as heḥemiru al atzman, minhaga, and halakhah pesukah, indicating that a variety of attitudes existed as to the severity of the requirement. Nowhere, however, is it presented as an actual rabbinic enactment, except for “country women” who cannot consult a rabbi.
Moshe Benovitz, “A Lifetime Companion to the Laws of Jewish Family Life and Man and Woman: Guidance for Newlyweds (review),” Nashim: A Journal of Jewish Women’s Studies & Gender Issues vol. 12, no. 1 (2006), 316.