In theory, the quickest time to complete each level is 7 days, except for levels 46, 47, 49, and 50-60, which (again, in theory) can be done in 3.5, since they contain few or no radicals.
So at one week per level for 46 of the level, and 3.5 days (half a week) for 14 of them, it is technically possible to complete it in 54 weeks, if you literally did every review and lesson the second it came up and never got an item wrong.

