Of course it was not a full time job but it is anyway a hell of a work.
Goethe first worked on Faust between 1773 and 1775.
In 1790 appeared a partial printing Faust, a Fragment.
Goethe completed a preliminary version of Part One in 1806. The 1808 publication was followed by the revised 1828–1829 edition, which was the last to be edited by Goethe himself.
Goethe finished writing Faust Part Two in 1832, the year of his death.
59 years indeed between the first fragment and the final version of the second part !