Prophet, peace and mercy of God upon him, used to fast so many days in succession that we said, 'He will never break his fast.' At other times he would go without fasting for so long until we said, 'He will never again fast;' except for two days, which he would fast even if they occurred during the times he was not fasting consecutive days.
This is what comes from authentic sources, a matter of "we said..." the perception of the companions r.a.
The hadees mentioned in Tabaqat is different,
Ibn Sa'ad wrote: “Sometimes the Prophet used to fast so much, as if he did not want to end it, and sometimes he would not fast for so long that one thought he did not want to fast at all.”
He wanted, and he did not want,....it opens the door for some disorders for people like alisina...NAOZUBILLAH, so I suggest everyone ,every Muslim to go only for the ahadees mentioned in 6 authentic books only, and if one knows arabic then check the translation as well,after authenticity.
If you do not know arabic, thn check 2 or 3 translations for better understanding of the whole hadees.
These Non Muslims have quoted ahadees even from some magazines so i am sick of all that now.I consider the source first, to discuss any hadees.