Assalaam alaykum. Is there any hint in the biography of our Prophet, sallallaahu ‘alayhi wa sallam, or the writings of the Salaf (pious predecessors) on the ideal number of times per week or month that a couple should have intimacy in a way that keeps both of them satisfied and also prevents them from getting bored of each other (since too little will keep them unsatisfied and too much will cause boredom)?

All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger. 

We did not find any mention of the ideal amount of intimacy in the books of the scholars. For benefit, please refer to fatwas 124328 and 126939 about the etiquette of intimacy and the rulings pertinent to it. These two fatwas underlined that the most likely correct view is that the optimal amount of intercourse the spouses should have is determined according to the woman's desire and the husband’s potency.

Scholars also highlighted that frequent intimacy is not disliked for those who have the needed ability. They relied on the following hadeeth: Anas ibn Maalik, may Allah be pleased with him, reported that the Prophet, sallallahu ‘alayhi wa sallam, used to pass by (have sexual relations with) all his wives in one night, and he had nine wives at the time. [Al-Bukhaari and Muslim]

Al-‘Ayni said, “It is deduced from the hadeeth that having much intercourse is not disliked for the person who possesses the potency for it...” [‘Umdat Al-Qaari’]

At the same time, they mentioned the harms of having too much intercourse, including that it drains strength, weakens the stomach and liver, causes indigestion, affects the color, causes tremors, harms the chest and lungs, and weakens the kidneys, and so on. These harms are cited by Ibn Muflih in his book Al-Aadab Ash-Shar‘iyyah. This is, of course, for the person who has no physical strength for it and for whom it is feared that he may cause such health hazards for himself.

Allah knows best.