I tried that route before----1 was a "charming medic" another a professor. ***HI WILLPOWER*** girls killed me (MAX charm mean less in other areas, incl Manip. ) +, I kept loosing willpower (UGH, happened several times) in teacher, etc, ie, Manipulative "Fail" cost me points elsewhere! Current run is a Criminal MAX Manip@start (asked in another post, but got no replies; Best "luck" so far, is the 2 variations of "criminal" (ie, PURE/embrace, & Rebel) all routes too many problems can't overcome.] For example, you can BUY more charm, but can't buy more Manip. pts; Also extremely hard to get back lost willpower (everything they talk about is very "Random", meaning you might try it many times, *IF* you're lucky only get 1 WP point! WP + Intel I think factor into training girls, & getting 2pts/day vs 4, is *HUGE* [can only teach 2x/day] can take months just to train 1 girl, in 1-2 skill! [much better if you can get 2pts/session]
PS alt route: when I did the hi charm (like you suggest) even *AFTER* books, etc Manip was still so low failed most of time. (not sure what odds are, but if you factor in those "other factors" ;-) you mention, maybe 60 manip. fails ~50% of time? Book (assume bad luck!) don't always give the same amount, & same w classes. Actually, isn't that CLASS singular? only "Miss Devious" class? if mem serves, nothing @ Acad give Manip pts.
again, cases here where too much spread/randomization is a BAD thing.
The "worst case" girls (Hi WP) charm usally FAILS on anyway, & they get more pissed off! Same thing w FEMINISTS. Manip. is only other way to affect them.
From many tries, my "pro-tip" , is Criminal, & MAX Intel, Manip. & WP @ start
(my 1st version was actually pretty good, but you can only have 6 slaves, & had to sell some b4 was able to get their Quests. If you plan to do most of the Quests, one must be very careful which slaves & in what order you buy them! lol