Is menstruation considered irregular if it is interspersed with interruptions and continuous bleeding, and is it permissible for an irregular woman to rely on dryness as a sign of purity?

Some scholars are of the view that a woman who observes purity through dryness may not hasten to perform ghusl (definition), and can wait for a day or thereabouts, especially if that is more comfortable for her. However, the authoritative fatwa (definition) is that a woman must promptly perform ghusl as soon as she observes purity by one of its two signs. If she subsequently sees a brownish or yellowish discharge, she should not consider it anything. But if she sees blood during a time when it is possible for it to be menstruation, then she reverts to being in a state of menstruation.