It's impossible to answer definitively because the requirements of confession are dictated by local custom; but in both the Catholic and Orthodox tradition, _communion_ should be taken once a year at minimum, and confession would ordinarily precede communion. According to an Orthodox Church of America site,
> Confession before each Eucharist is a common practice in Russia, Romania, and Ukraine. It developed in the past centuries due to the lack of frequent communion among the faithful. At some point in the past several centuries, people began to receive communion only once – maybe twice – a year.
The literary importance of the OP's question, in my mind, is not what the requirements of the tradition are but how the statement shows us both the (ir-)religious nature of the one character and how that is perceived by the other (whether herself genuinely religious or merely virtue signaling).