If the menstrual blood stops, is what comes after it always considered irregular bleeding, or is it possible for menstruation to occur more than once in a month?

The questioner : My question is: if there is an interval between the menstruation and what comes after it, does this prove that it is definitely irregular bleeding, or is it possible for menstruation to come intermittently?

The Shaykh : Yes, menstruation—may Allah reward you—has a sign, as he (peace and blessings be upon him) said: And in another wording: —peace be upon you—menstrual blood is black and is recognized by women, or it has a known, foul smell. Then, when this blood first comes, it arrives with force and in large quantity, and it has this sign: it is black and recognized. Then, as each day passes, it begins to weaken and its color fades and fades until it becomes like a stain after a stain, and then purity comes, meaning a white, liquid substance, which is the sign of the end of menstruation. If a woman sees this sign, it means she is pure. If she sees blood one or two days after that, it is not menstrual blood, because it has ended, and menstruation does not come twice in the same week or in the same month, I mean. So what can happen here? It is possible that the custom differs; a woman's custom differs, and the difference may be in the number of days of menstruation, or it may start at the beginning of the month and then start in the middle or at the end. These are matters in which women are, of course, more knowledgeable than men in general, but this is if they are jurists in this specific issue, and jurisprudence requires them to know that menstrual blood is black and recognized, and that the sign of purity is seeing the white discharge.

The questioner : And everything that comes after that is irregular bleeding.

The Shaykh : Irregular bleeding.