One of the significant changes for the faithful in the Code of Canon Law which was promulgated in 1983 was the permission to receive Holy Communion more than once per day. In the past the law set certain conditions, such as participation in a funeral, marriage or ordination Mass.
This is canon 917.
The exception to this is the one given in the law itself, canon 921, 2.
"2. Even if they have received Communion in the same day, those who are in danger of death are strongly urged to receive again."
Thus, Communion given as Viaticum may be received at any time.
Prior to 1983 it was only once per day. Even that was not a practice common in the Church.
It was only in 1905 that Pope Pius X issued 'Sacra Tridentina'.
"The question concerning the dispositions required to receive the Eucharist daily; so that this practice, so salutary and so pleasing to God, not only might suffer no decrease among the faithful, but rather that it increase and everywhere be promoted, especially in these days when religion and the Catholic faith are attacked on all sides, and the true love of God and piety are so frequently lacking."
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As can be read in the Catholic Encyclopedia (1909):
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From the Catholic Encyclopedia:
"Good Christians still communicated once a week, down to the time of Charlemagne, but after the break-up of his empire this custom came to an end. St. Bede bears witness to the Roman practice of communicating on Sundays and on the feasts of the Apostles and Martyrs, and laments the rarity of reception in England (Ep. ad Egb. in P.L., XCIV, 665).
Strange to say, it was in the Middle Ages, "the Ages of Faith", that Communion was less frequent than at any other period of the Church's history. The Fourth Lateran Council compelled the faithful, under pain of excommunication, to receive at least once a year (c. Omnis utriusque sexus). The Poor Clares, by rule, communicated six times a year; the Dominicanesses, fifteen times; the Third Order of St. Dominic, four times. Even saints received rarely: St. Louis six times a year, St. Elizabeth only three times."