In days gone by there were very many sequences, but in the Missal of St. Pius V these were reduced to 3, for Easter, Pentecost and Corpus Christi, plus Masses for the Dead, if you count the Dies Irae as a sequence. Nowadays we sing it more often than in the past, as we use it as a hymn for the last week of the Church’s year. We also sing a variety of sequences, in whole or in part, at Benediction or under the guise of hymns. In addition, of course, as Benedictines we have a special sequence for the feasts of St. Benedict.