Canon Law:
Can. 988 §1. A member of the Christian faithful is obliged to confess in kind and number all grave sins committed after baptism and not yet remitted directly through the keys of the Church nor acknowledged in individual confession, of which the person has knowledge after diligent examination of conscience.
§2. It is recommended to the Christian faithful that they also confess venial sins.
Fine, but you haven’t quoted where in Canon Law it says that the penitent must revisit the “number of times” (of a committed mortal sin) of a past confession, when he or she realizes later the
number was inaccurate. What must be revisited is the category (kind) of the forgotten grievous sin, not the number of the sin – unless, again, there was a portion of that previous confession that addressed number overtly. (Priest asked about frequency, and/or frequency was an essential part of the counseling given.)
A mortal sin is just as mortal if it is committed only once as when it has been committed more than once. It does not add to the gravity of that sin to have committed it several times. It indicates repetitive behavior, but does not change the seriousness of the sin. That is why the previous confession does not need to be revisited specifically for the quantitative aspect. The only exception – again – is for two reasons: (1) 'Father, I erred last time with regard to number of times. You said that you were glad I had committed this sin no more than once. I now remember I had committed it three times. I thought you should know that." or (2) “Father, although you did not inquire about number of times I committed ________ [serious sin], I realize now that I should have told you that I’ve been doing ______ several times a week/a day (etc.). It wasn’t just once, and this time also, it’s not just once, so I know I have a problem with this.”
So in one example I just gave, it’s to correct a misimpression that was specifically discussed in that previous confession (i.e., frequency). In the second example, it’s a matter that the penitent is bringing up for some prudent counseling: the penitent is choosing to use (appropriately) the sacrament for spiritual counseling.
Otherwise, if the priest does not bring up the matter of frequency when the penitent doesn’t offer it, it is not necessary to revisit that confession for quantity reasons because it has been judged not important by the priest.
It invites scrupulosity to suggest that penitents should revisit confessions for non-canonical reasons.
In order of importance, the important elements of this sacrament, on the part of the penitent, are:
(1) The quality of the contrition. That is not only stated specifically in the Catechism; it is also quite scriptural.
(2) The accuracy of the sins named: the action done, the context in which it was done, and if possible, the motivation or other circumstance, including who else was involved, injured, and their relationship to the penitent, etc, if this is an aspect.
(3) The approximate frequency of the sin. It is the least important element of the penitent’s participation.
For a sacrament – any sacrament – to have valid integrity in and of itself, in that moment in time, it must possess the necessary matter and form. In this sacrament the matter and form are broad: they are the confession of sins (with assumed sorrow and assumed purpose of amendment) and the providing of absolution. “Number of times” is not essential to the validity of the sacrament; therefore, it is not necessary to revisit a confession for just this, except in cases such as described above.
Number of sin occasions is part of rubric or protocol. Like the absolution formula itself, if it is slightly inaccurate, the confession is not invalidated or compromised, and therefore need not be revisited on that aspect alone.
You will find various rubrics or protocols for baptisms and for weddings. As long as the matter and form are not compromised for those, those sacraments also are valid and are not revisited or re-performed or formally corrected by the participants, after the fact.
If any Catholic personally feels compelled to revisit for number of times, that is his or her prerogative, but it is not required. And specifically for the scrupulous, it would be contra-indicated.
