Sabbath, worship and two services

Pastor Robert Godfrey writes:

The privilege and blessing of meeting with God in public worship is seriously undervalued in our time. Too often it is thought that small prayer meetings or Bible studies, missionary reports or musical presentations can replace public worship as activities that are more spiritually profitable. Such activities may indeed be useful, important and inspiring. But they cannot replace the central importance of public worship.
If Reformed Christians can come to clarity on the value and importance of public worship, it should be easy to answer the oft-asked question, “Do we have to have two worship services on the Lord’s Day?” Our first answer is the obvious: There is no specification in the Bible as to how many services are required on the Lord’s Day. But our second answer should be equally obvious: What could be more proper or valuable than worshipping God on His day?
The Reformed practice of two worship services on the Lord’s Day arose not out of a legal requirement to have two, but out of an eager desire to grow in grace and a recognition that the best way to grow in grace is through the preaching of the Word and the reception of the sacraments. If we are content with one worship service on the Sabbath, we should look at our motivations and priorities as well as at our theology. Perhaps we ought to ask, why can we have only two services?
The Reformed churches have found two services on the Lord’s Day to be a great blessing. One service has often been given to the teaching of the catechism and the grounding of the congregation in the basics of the Christian faith. Some churches have used the second service for more frequent administration of the Lord’s Supper as well as preaching. Clearly there are many ways in which two services can build up the people of God.

You can read the entire essay here.
For clarity, when Rev. Godfrey speaks of two services he is speaking of two worship services for the same body of believers.  In other words, the expectation is that those believers who worship in the AM will do so in the PM as well.  The practice of a second evening service marketed toward a separate niche demographic (i.e. youth) is foreign to the covenantal witness of Scripture confessed in the Reformed tradition.
It is interesting (and indicting) to note that our Presbyterian, Reformed, Anglican and Lutheran communions historically took observing the fourth commandment seriously – i.e. sanctifying the Lord’s Day.  Has the practice waned for solid theological reasons (revisions) or out of worldly convenience?  Or for the sake of being missional (read: seeker friendly)?  By God’s grace, may there be a renewal of Lord’s Day observance for our own spiritual health and our witness to a world that is dying for want of true REST.
Another essay on the Sabbath by Godfrey can be read here and one by Prof. John Murray, here.