Daas, that’s only chumash, and it’s bedieved; the rambam says it’s better not to do it, but if she does, she gets schar. For anything else, the rambam doesn’t say that she gets schar at all in the context of limud hatorah, and it’s in fact assur to teach Torah shrle baal peh. Other things, like hashkofa and mussar, are encouraged by the Gaon to be learned.
Bais yaakov and seminary weren’t started to fulfill a mitzvah of talmud Torah: they were started to teach and strengthen yiddishkeit. Some girls aren’t strengthened by studying; some are so turned off by it that they resort to television, movies and goyishe music to relax from the stress of academics in high school… In such cases, they are doing far more harm than good. If instead of academics, they were offered chesed projects, mussar groups, domestic skills like sewing, music, acting, etc… Lots of things can be made to strengthen yiddishkeit for women besides pushing rambans.