The value of regular confession is at least twofold:
(1) It helps to prevent us from slipping into a chronic unrepentant, unconfessed venial-sin habit. And such habitual venial sin easily slips into mortal sin – more easily than perhaps we realize.
(2) To me, this is the bigger issue: frequent confession refines our awarness of our own sin: its root causes (often more important than the sin itself – rather, the stubbon motivators, or the cardinal sins, the distorted & disordered reasons we do things, which is usually to serve ourselves at the expense of God & others). When we enter into the sacrament more frequently, we are more aware of the enormity of our sin (in its effect upon others, in its injury to our own holy destinies). That’s an irony of frequent confession, but it’s a fruitful irony: that little by little we no longer see ourselves as “only committing venial sins.” We stop triviliazing and rationalizing so much, and tend to accurately realize how serious, how impactful, many of our everyday tendencies are. In this way, even though the sacrament is not spiritual direction, it has as one of its by-products a kind of spiritual formation: it helps us peel away the layers of dishonesties, deceptions, pretensions, excuses, and compromises to truth. It gives us strength and vision to stand increasingly naked before God, which in turn allows us more efficaciously to avail ourselves of his deeply healing mercy.
Confession should never be a superficial exercise (a rote or routine list). If it’s not genuinely self-reflective, it has little value to us and even less value to God, in his desire to have a dynamic & ever-intensifying relationship with us.