I think that's probably correct. 4 courses per year is equivalent to 30 semester units in the US (2 semesters of 15 units each). You can't do it in less than 3

I think that's probably correct. 4 courses per year is equivalent to 30 semester units in the US (2 semesters of 15 units each). You can't do it in less than 3 years, due to the university rules which won't let you take more than 4 courses per year.