I share joint custody with my ex. He has Tuesdays and Thursdays, plus every other weekend. I have Monday Wednesday and every other weekend. During the summer we go one week at a time unless we have a trip or something planned. This arrangement was made when my son was 5. It worked great then, but he's 13 now and he hates the going back and forth.
I think that the alternating 3/4 day schedule might be the best for the child. If the judge has already decided, then there is not much else. The 2 weeks with one and 2 weeks seems excessive, particularly for a child that age. A 3 year old should not have to go 2 weeks at a time only seeing the other parent for 3 hours a week.
My cousin has the 3/4 day arrangement for his 2 kids and they handle it very well and are well adjusted.