Does the required waiting period (Iddah) necessitate three full cycles, whether menstruation or purification?

Primary text

The apparent meaning of the verse {And divorced women shall keep themselves waiting for three periods} necessitates a full three cycles. Those who interpret 'quru'' as purification periods do not require three full cycles, as they permit satisfaction with two full purifications and a part of the third, thus contradicting the apparent meaning of the text. Conversely, those who hold 'quru'' to mean menstruation require three complete cycles, thereby aligning with the apparent meaning of the text, which makes their interpretation preferable.