Yo @zappallbugs found out that you can talk to teagan and maria at bd falls without fucking them AND do the swim training with viviane afterwards. Free points
As far as I can see this nets you only one point in the end:
"Get a hardon and show them your mighty cock": -> +2 for Maria, +1 for Teagan
"You can do better than that teach...": -> ends up in a fuck and 1 hour, unless you missed points on both of them
"Yeah, I'm da man, I'm DA MAN!": -> -1 for Teagan, so no net gain on her
"Err, yes, on top of enjoying the superior intellect of women that is.": -> -1 for Maria, so you end up with a net gain of 1 for her
"Yeah, and an ass man too. An titass-man is what I am.": -> ends up in fucking Maria and 1 hour, unless you missed points on her
But I will look further into it. That one point on Maria may be critical as you can only get 2 points on her in the library scene on day 5.
Edit: the "Err, yes, on top of enjoying the superior intellect of women that is." path currently doesn't work. There is a bug there that makes you go in circles. I reported it to Tim.
Edit2: Tim accepted the bug and corrected it. So this approach is valid. Thanks, bigguts, for putting me on this trail. It does look promising.
Edit 3: that one point turned out to be highly relevant. It enabled me to do another 15-girl run. But the first one I ever did without Katsumi. So she remains available for another time.