I'm not sure how It's code but, for me, it's not working properly. The adjacent field is useful since it's not given the adjacent field.
I think the purpose for adjacent field is to inform where map to go to se the next part of the area. But, when you have rotation on the index polygon the result show by the map series or data driven pages "calculate adjacent fields" is more than 50% out of the right value.
So my idea is to use the rotation field to calculate the value we need instead of doing it manually to represent the adjacent field.