Is it permissible to act upon the school of thought of Imam Al-Awza'i, who holds that the maximum duration of menstruation is seventeen days, in the event that the menstrual period extends to that duration, knowing that the questioner is fifty years old, unmarried, and finds it difficult to distinguish between menstruation and irregular bleeding (istihada)?

The maximum duration of menstruation according to the Hanafis is ten days, while according to the other three Imams, the duration is fifteen days. It is also reported from Ahmad, Al-Shafi'i, and Ibn Hazm that the maximum duration of menstruation is seventeen days. Ibn Hazm argued that whenever a woman sees black blood, she should consider herself menstruating unless there is a text or consensus to the contrary. If the latter opinion is more lenient for the woman, then there is no objection to following it.