"K, what is the frequency in the Orthodox Church?"
It depends on the jurisdiction and even the parish. Some "rules" say four times a year, others once a year. Some jurisdictions require confession before every communion. The frequency rate I would say runs from never (a lot of people, especially older cradle Orthodox types among the Greeks at least) to once a month or so. Converts and younger folks seem more faithful to the sacrament. You should know that Orthodoxy makes no distinction between mortal and venial sins as such.
I figure I can go about 2 weeks before I start messing up even more than usual. This once or twice a year isn't getting it for me.