Hmm... I'm not sure, really. I'm *personally* not a huge fan of the paths locking out scenes or encounters, rather I'd prefer if they were more about flavor. That's up to people to weigh in on, of course. I guess it adds replayability.
Secondly, as for making her overly grindy... I don't know. As of now, Jennings was made much more time-consuming and intricate, and I'm not sure if it really made the progress more enjoyable.
If it's possible, I rather imagine a kind of progression that starts very slow but then gains speed about two quarters in or so. Leave off the more explicit scenes and the more explicit lustfulness for later, but once it's out, it's out.
Not sure if this made any sense, lol.
(As for my ideas on actual concrete progression, see my comment about the two first scenes being watching her masturbate in the window and then later kissing her earlier in the thread).