Must I fast for only ten days, or more, after repeating the sin dozens of times following a vow to fast for ten days upon its repetition?

If the intention behind saying, "If I do such-and-such again, I will fast for ten days," was not a vow (nadhr), then fasting is not obligatory upon committing the sin. However, if it was intended as a vow, then it becomes binding and is called a vow of obstinacy (nadhr al-lajāj). In this case, the woman has the choice between fasting for ten days or performing the expiation for an oath (kaffārat yamīn) once, even if the sin is repeated. It is advisable to repent and stay away from sins.