The Confiteore, I confess

Did you know that, if you have not committed mortal sin you don't need to go to the sacrament of confession but once a year.  (CCC #1457) Why is that?

Well, that's because venial sin is forgiven in the Confiteor. The Confiteor is the prayer that we pray together at the beginning of Mass. It is also known as the Penitential rite or general confession and is not simply recited for a pleasurable exercise. Our venial sins are remitted when we pray this prayer in the beginning of the Mass.

I confess to almighty God,and to you, my brothers and sisters,that I have sinned through my own fault,in my thoughts and in my words,in what I have done, and in what I have failed to do;and I ask blessed Mary, ever virgin, all the angels and saints, and you, my brothers and sisters, to pray for me to the Lord our God.

It is a public confession in the presence of a priest.

Here's what St. Thomas Aquinas, the Angelic Doctor says:

I answer that, As stated above (Article 2), no infusion of fresh grace is required for the forgiveness of a venial sin, but it is enough to have an act proceeding from grace, in detestation of that venial sin, either explicit or at least implicit, as when one is moved fervently to God. Hence, for three reasons, certain things cause the remission of venial sins:  

first, because they imply the infusion of grace, since the infusion of grace removes venial sins, as stated above (Article 2); and so, by the Eucharist, Extreme Unction, and by all the sacraments of the New Law without exception, wherein grace is conferred, venial sins are remitted.                      Secondly, because they imply a movement of detestation for sin, and in this way the general confession [i.e. the recital of the Confiteor or of an act of contrition, the beating of one's breast, and the Lord's Prayer conduce to the remission of venial sins, for we ask in the Lord's Prayer: "Forgive us our trespasses."  

Thirdly, because they include a movement of reverence for God and Divine things; and in this way a bishop's blessing, the sprinkling of holy water, any sacramental anointing, a prayer said in a dedicated church, and anything else of the kind, conduce to the remission of venial sins.Summa Third Part, Q87, art 3

So, if you happen to be late to Mass and miss the Confiteor, your venial sins are forgiven when you recite the Our Father, or take communion.

And so, it isn't necessary for a faithful Catholic to go to the sacrament of confession more than once a year unless he has a mortal sin on his soul.

However, the sacrament of confession is recommended as frequently as possible because it is an outpouring of God's grace, a gift, a participation in God's life. Why would we want to minimize that? We should want that as often as we can get it.