For ABBA or ABAB placement, personally I will refer ABAB considering all factors, including SA/SB. For better matching, 2 or more dimension will be referred.
Why people uses ABBA, I guess it could relate to an old document of TI about matching and common centroid. In that document, ABBA is common centroid and symmetry, while ABAB is asymmetry. So it might become convention for along while, just my guess ^_^
About the simple dimension you've mentioned, I think it's mostly related to operating freq. High speed design will refer simple matching structures.