Can one perform the Duha prayer with an unlimited number of continuous rak'ahs?

Al-Bayhaqi and Al-Darimi narrated from Abu Dharr that the Prophet, peace and blessings be upon him, said: "There is no servant who prostrates to Allah a single prostration except that Allah raises him one degree by it and removes one sin from him by it." It is permissible for a person performing supererogatory prayers (nafilah) of an absolute nature to conclude their prayer after one rak'ah, or to add as many rak'ahs as they wish. Even if they pray a number they do not know and then conclude, their prayer is valid. As for specified supererogatory prayers, such as Duha prayer, they must only be performed according to their prescribed form, which is in units of two rak'ahs (shaf').