IMO the advantage of 3A for ladies is that you can have one in SP and two in FS, while if you have two quads that grant you three ultra-c elements, like Anna for instance, you have to put them all into free program, which is raising the probability of an error. On the other hand even with a smaller error you have still some advantage like Anna in Russian nationals. Of course having let's say 3A and one quad can be more advantageous than two quads.
For Sasha, if she would gain stable 3A, it could be advantageous to do just the one in SP and then two or three quads in the free without 3A.