Is Heidelberg Catechism Required?

Charles, 

Thanks for your question.  I am unclear if you are a member of the CRC or RCA.  The two denominations have slightly different relationships with the Heidelberg Catechism and requirements regarding its preaching.  I can only speak to the CRC's position. 

In the CRC every officebearer (pastor, elder, deacon) is required to sign a covenant which states: "We also affirm three confessions—the Belgic Confession, the Heidelberg Catechism, and the Canons of Dort—as historic Reformed expressions of the Christian faith, whose doctrines fully agree with the Word of God. These confessions continue to define the way we understand Scripture, direct the way we live in response to the gospel, and locate us within the larger body of Christ."  The full Covenant for Officebearers is found here: https://www.crcna.org/resources/church-resources/liturgical-forms-resources/ordination-installation/covenant-officebearers

As for whether or not the Heidelberg Catechism should be included in our preaching.  According to Article 54 of the Church Order: "At one of the services each Lord’s Day, the minister shall ordinarily preach the Word as summarized in the creeds and confessions of the church, especially the Heidelberg Catechism". The full church order can be found at: https://www.crcna.org/sites/default/files/2017_church_order.pdf 

Of course this assumes that there are 2 services every Sunday.  If your congregation meets only once then I think your pastor is correct in interpreting the spirit of this church order by preaching through the catechism once every three years. 

So it seems that your pastor is acting appropriately from a CRC perspective. 

There are guidelines available for pastors, councils, congregations, and individuals to challenge any doctrinal or church order stance.  I suggest you begin by discussing your concerns with your own elder. 

I looked up the position of the RCA and found the following in their Directory for Worship: "Heidelberg Catechism 
The Book of Church Order of the Reformed Church in America requires that all the points of doctrine of the Heidelberg Catechism be preached every four years. Although the ecumenical lectionaries cover the points of doctrine, those who wish to follow the sequence of the Catechism may refer to the Liturgy and Psalms,1968, which has a lectionary for such catechetical preaching. Its advantage is that it offers the congregation a structure of theology and a familiarity with one of the finest of our confessions of faith."  You can find the full Directory for Worship here: https://www.rca.org/resources/directory-worship