... is what Vatican II mandated in the Liturgy. A good example today. The admirable S Laurence ORDO, giving the rite of around 1939, gives S Praxedes. Pius XII introduced S Laurence of Brindisi; so the SSPX ORDO gives him with a commemoration of her. Thus do fading cults give partial but not total place to growing cults. The life of the Church moves on but without consigning the older to the rubbish dump.
I think there is an important theological point somewhere here.