How often should someone go to confession?
Your question uses the word “should,” which can mean “ought to” or it could mean “must”. Church law answers the meaning of “must” Canon Law # 989 states: “All the faithful who have reached the age of discretion are bound faithfully to confess their grave sins at least once a year.”
I will address the “ought to”. Here the answer depends on the individual and their sins. If someone is aware of having committed a mortal or serious sin they ought to go to confession as soon as possible – even that day if practical.
Given the positive effects of the Sacrament, I would personally recommend, even without serious or mortal sins, one would want to go frequently — by that I mean weekly or monthly to confess their venial or lesser sins as a way of seeking spiritual growth. Let me explain by mentioning the effects of the sacrament of Penance. According to the Catechism of the Catholic Church:
1468″The whole power of the sacrament of Penance consists in restoring us to God’s grace and joining us with him in an intimate friendship.” Reconciliation with God is thus the purpose and effect of this sacrament. For those who receive the sacrament of Penance with contrite heart and religious disposition, reconciliation “is usually followed by peace and serenity of conscience with strong spiritual consolation.” Indeed the sacrament of Reconciliation with God brings about a true “spiritual resurrection,” restoration of the dignity and blessings of the life of the children of God, of which the most precious is friendship with God.
1469 This sacrament reconciles us with the Church. Sin damages or even breaks fraternal communion. The sacrament of Penance repairs or restores it. In this sense it does not simply heal the one restored to ecclesial communion, but has also a revitalizing effect on the life of the Church which suffered from the sin of one of her members. Re-established or strengthened in the communion of saints, the sinner is made stronger by the exchange of spiritual goods among all the living members of the Body of Christ, whether still on pilgrimage or already in the heavenly homeland…
As the Church teaches “Christ who died for all men desires that in his Church the gates of forgiveness should always be open to anyone who turns away from sin.” Why not take full advantage of the graces God wants to pour out upon us? We wouldn’t think in our culture of not cleaning our physical bodies regularly, why should our spiritual bodies be forgotten except for once a year or less?