I think some priests got out of the habit of going through the Act of Contrition with the penitent when the younger people stopped learning the traditional words (“O my God, I am heartily sorry for having offended thee…”). I learned a 1970’s version which I still say whether or not the confessor assigns it (mine doesn’t). The important thing is to make SOME act of contrition whether or not one composes the words oneself. Making an Ignatian Examen of conscious at least once a day is a good way to stay in the habit of doing this.