question #3 Sahih Muslim 1157a, Book 13, Hadith 230 : What can be inferred about the Prophet Muhammad’s (ﷺ) approach to voluntary fasting?

The Messenger of Allah (ﷺ) did not fast throughout any month except during ramadan. And when he observed fast (he fasted so continuously) that one would say that he would not break (them) and when he Abandoned, he abandoned (so continuously) that one would say: By Allah, perhaps he would never fast.