My understanding from
Old dog's posts from L&P is that the boarding school route for Dylan has it's own storyline, and that it
is smaller than the blackmail route. But it may well be a case of quality over quantity - like the chicken fight on the boarding school route, which is the closest to sex Dylan achieves, and more then he does on the blackmail route. Just not with Sophia.
Keep in mind also that the roadmap doesn't say how many Dylan events are on each day, and of which type they are. On the non-zero weekend days he could have several events, and different events depending on the route.