Actually, in the Reformed churches the Holy Communion is in most cases only the exceptional appendix to what is called “ordinary” worship; that is, the service of the word in which preaching has the central place. The error in this Reformed custom is not so much in splitting the service into two quasi-independent parts as it is the downgrading of the second section – the sacrament – to the rank of an occasional appendix to the first – the word – considered as normally complete and sufficient. This is a lamentable rejection of the apostolic custom of celebrating Holy Communion every Lord’s Day, a practice no church of the “Catholic” type has ever abandoned.
Richard Paquier, Dynamics of Worship: Foundations and Uses of Liturgy, pg. 158
So, Holy Communion is put off to a monthly, quarterly, or even yearly event in Reformed circles because we want to keep it “special.” Pfft! Every single Lord’s Day is special because it is the day the Lord meets with us, speaks to us, and feeds us. It is on Sunday because it the first day of the new week (when set off against the Sabbath Day of old). In other words, it is God’s day that he has set apart for the grand task of re-creation. Are we going to make things more special than that?