How many times must a menstruating woman check for her purity when it is probable that her menses have ceased after the time for prayer has begun, and is checking once at the beginning of the time sufficient?

A menstruating woman must check for purity when it is probable, especially during prayer times, before going to bed at night, and before the prayer time expires, so that she does not miss a prayer. This obligation is extended at all times, and the obligation narrows until there is only enough time left for ghusl (definition) (ritual bath) and prayer.