Is holding the beard always Sunnah, or only when preoccupied with an important matter, as mentioned in the hadith narrated by Aisha?

Ibn Hibban and Ahmad narrated from Aisha, may Allah be pleased with her, that when something troubled the Prophet, peace and blessings of Allah be upon him, he would take hold of his beard. This chain of narration contains weakness, but it has another path that strengthens it, which is what Abu Al-Shaykh narrated from Aisha, who said: "When Messenger of Allah, peace and blessings of Allah be upon him, felt intense grief, he would frequently touch his beard." Shu'ayb Al-Arna'ut and Al-Albani have graded it as hasan (good).

This action is among the natural or habitual actions, and not intended for legislation or worship, similar to people's habit of pulling their mustache when angry, as Umar ibn Al-Khattab did. This type of action is not taken as an example to be emulated in worship; rather, it is among the permissible actions. Conforming to it is permissible and not considered an act of worship, but it is good. Performing it indicates permissibility, not legislative enjoinment.