I feel like that getting S isn't really that hard, and you don't need many of S videos anyway, since money completely ceased to be an issue from the first couple of videos.
What is actually slow and repetitive is grinding of exp points for all her parts and fetishes. Not only progression don't show up until you end the scene, each different position have different max possible accumulated points, that sometimes make you do actions for nothing. And with fully grinded up exp, you would need to purposefully fail to get anything other than S anyway.