What is the Islamic legal duty regarding a wife's visit to her mother, and what is the specified number of such visits?

Among the good companionship of a husband is that he helps his wife honor her parents and maintain ties of kinship. Scholars differed regarding the husband's permission for his wife to visit her parents: some considered it recommended, while others deemed it obligatory if the parents are unable to visit her. As for the frequency of visits, it appears that this is determined by custom. Some Hanafi scholars stated that she should be permitted to visit them "from time to time, as is customary." Therefore, the closeness or distance between visits depends on custom and varies according to circumstances, benefits, and harms, such as the mother's proximity or distance, or her illness and need for care. Both spouses should communicate and consider each other's circumstances.