I understand the part where sins are forgiven based on Christ’s suffering 2000 years ago in Jerusalem, and I can appreciate that it’s a complicated subject.
So, in trying to further understand penal substitution, does it mean that we as sinners don’t have to worry about our sins because Jesus suffered for all of them, even those we all (in our time) commit? This doesn’t seem very Catholic to me, since the debt owed by sin still has to be paid, maybe in Purgatory, if needed, by us. Why would we want to put that on Our Lord, and further increase His suffering.

It seems that the penal substitution make Jesus required to keep paying for all of our sins, so that we don’t have to suffer or pay for them at all, which seems rather Protestant to me, and is a way to discount the reality of Purgatory, and works needed to grow in holiness. Am I understanding it correctly at all?