 According to a tradition brought by Hai Gaon, he held the position for 60 years, though given his approximately 75-year lifespan it is possible this number was rounded upwards.According to the same tradition, these 60 years were so symmetrically apportioned that each tractate required six months (including a single Kallah) for the study of its Mishnah and the redaction of the traditional expositions of the same (Gemara), totaling 30 years for the 60 tractates.The same process was repeated in the next 30 years.