Whoever maintains that she is obliged to purify herself only once each day has most likely imposed that duty because of lingering doubt, and I know of no transmitted report to support it.

Fifth Issue
The scholars have differed over the permissibility of marital intercourse with a woman experiencing istiḥāḍah, and they have formed three positions:

1. A group holds that intercourse with her is permissible. This is the view adopted by the jurists of the major centers and is reported from Ibn ʿAbbās, Saʿīd ibn al-Musayyib, and a number of the Successors.

2. Another group says it is not permissible; this is reported from ʿĀʾishah and is the opinion of al-Nakhaʿī and al-Ḥakam.

3. A third group contends that her husband should refrain unless the bleeding continues for an extended period. This is the view of Aḥmad ibn Ḥanbal.

The root of their disagreement is whether the permission granted to her to perform the prayers is merely a concession because of the emphatic obligation of ṣalāh, or whether it is allowed because, in legal terms, she is deemed pure. Whoever regarded the ruling as a concession forbade her husband to approach her, while whoever deemed her legal status to be that of one who is pure permitted intercourse.

In short, this is a matter about which the sources are silent, and distinguishing between a brief and a prolonged duration of bleeding is simply juristic preference (istiḥsān).