Come on, people, the OP said he could not recall what the event was called. Let’s give the parish the benefit of the doubt and assume it’s one of those penance services where the preparation is done together and individual confessions are heard by lots of priests after the group portion.
To the OP: These services are designed for the people who only go to confession in Advent and Lent to prepare for Christmas and Easter. Since you confess regularly, it would be an act of charity for you to stay away from this service, leaving more time for the twice-a-year people. There is nothing here that you need, since you (thanks be to God) confess often.
On the other hand, if you have some friends you are trying to bring to confession, this might be a good opportunity. Unless it really IS general absolution, which would be illicit, as others have pointed out.
Betsy