It is probably obvious just post my experience: I just labbed her potential block counters pairing with parry.
12..4
B4..3
Parry will not save you ass at all. So picking parry for covering gaps is not a reason.
Against a flawless block opponent staggering 12 looks viable though. The stagger is noticable but during the war and preparing to flawless block it is difficult to immediately react with a good button to eliminate any Skarlet follow up.
Staggering B43 looks pretty the same.
And if the opponent looks for staggering and try to counterpoke or advance - parry cancel can help in that case! That can lead into huge mind games if anybody cares about it.
But I guess it is the case in case of other characters too.
I do not know if anyone will master flawless blocking Skarlet's normals but as some of them are slow enough to be able to do it. But during the heat of the battle that's unlikely.