Is an agreement between spouses on specific invocations (dhikr) to be recited separately (the husband at his workplace and the wife in her home) considered an innovation (bid‘ah), given that no specific number or time is designated?

If the adhkar (remembrances of Allah) are legislated and established by the Sunnah, such as the morning adhkar, then there is no harm in agreeing to recite them and adopting them as a daily wird (litany) for remembrance and competition in good deeds, based on the Almighty’s saying: "And enjoin prayer upon your family and be steadfast therein." However, if the adhkar are not legislated as a wird, it is not permissible to adopt them as such. One must restrict oneself to the legislated awrad (plural of wird), such as the morning and evening adhkar and the adhkar of prayer, or reciting a specific portion of the Quran with the intention of encouragement, not due to believing in the virtue of the number itself.