That's not exactly what happens today.
Typically, women who are preparing to convert to Judaism, do so in the context of an observant Jewish community.
While it is accurate that the rav of that community will ultimately testify before the beis din that this woman is ready for conversion, that only happens after many interactions (over a few years) with the rav, his wife, and other families within the community.
The many hours of discussion, informal instruction, questions and answers, and personal bonding will usually happen with a female (often the rav's wife, but it could be any respected female in the observant community).
To borrow a phrase, "It takes a village" to make a convert.