I haven't played this but watching RK constantly fail gives me an urge to try this. Can't be that hard...
What I've gathered from watching the videos:
1) Traits affect success rate in tasks and/or give additional dialogue options for more xp (noticing things not giving up etc)
2) Abilities govern how much skill you get from succeeding in an activity
3) Literature/Science is mental, fashion/sports is physical. Art/music is both physical and mental.
4) When you perform an activity, others increase/decay slightly. It seems like doing mental stuff drops physical and vice versa. Art seems to randomly increase/decrease all stats, but mostly increase.
5) When you rest, all skills deteriorate slightly
6) Physical/mental exhaustion is generated by failing activities. (the few times RK went a whole week with no failures, his exhaustion didn't drop
7) So getting the lucky/charmed trait which s supposed to govern success rate in activities means you can get more activities in before mandatory deterioration during rest
8) Resting seems to fill ~25% of both bars per day. so either rest uring weekend at 50% or at 75% and have an activity sat or sun
9) The girls seem to have stats they value, as the friendship/love conversations appear to be triggered when gaining ranks in classes, not just after dates
10) Suzu is probably math/science, alice is music/art, rena is probably literature etc.
11) Special activities seem to substitute a regular activity and add +popularity on top. Probably because you're doing them with people.
It should be pretty straightforward to game your way to a perfect run. but it wouldn't make for a terribly entertaining let's play. Let's be honest for a second -- we're all here to laugh when 47-chan fumbles.