Do Presbyterian Protestants have a 'day of rest' or a 'day of religious works'? My own experience, growing up in Presbyterian Protestantism (four generations of Church of Scotland ministers) gave me the distinct impression that many influential people in that section of Christendom were treating 'Sunday' or 'the sabbath' as an opportunity to load heavy burdens on the congregation.

I remember exhortations along the lines of 'you must think spiritual thoughts all day on a Sunday' and 'you must not let your mind wander'.

Does Presbyterian Protestantism really believe that the sabbath is to be 'rest'? Or do they believe it is one day out of seven in which maximum religious exertion should occur?


  For he that is entered into his rest, he also hath ceased from his own works, as God did from his. Hebrews 4:10.
The position of the Westminster Confession of Faith regarding Sabbath day observance may help to explain why you were exhorted to “think spiritual thoughts all day on a Sunday” and that “you must not let your mind wander”:


  
  As it is the law of nature, that, in general, a due proportion of time be set apart for the worship of God; so, in His Word, by a positive, moral, and perpetual commandment binding all men in all ages, He hath particularly appointed one day in seven, for a Sabbath, to be kept holy unto him: which, from the beginning of the world to the resurrection of Christ, was the last day of the week; and, from the resurrection of Christ, was changed into the first day of the week, which, in Scripture, is called the Lord's Day, and is to be continued to the end of the world, as the Christian Sabbath.
  This Sabbath is then kept holy unto the Lord, when men, after a due preparing of their hearts, and ordering of their common affairs before-hand, do not only observe an holy rest all the day from their own works, words, and thoughts about their worldly employments and recreations, but also are taken up, the whole time, in the public and private exercises of His worship, and in the duties of necessity and mercy.
  https://www.rts.edu/Site/About/Reformed_tradition/WestminsterConfession/wc_ch21.aspx
  


It has been my observation that SOME Protestant denominations place great emphasis on what could be described as “maximum religious exertion” by running around like headless chickens on a Sunday, from dawn to dusk, participating in church-related activities.  However, the Westminster Confession does advocate observing a day of rest from secular activities (including employment and recreation).  No doubt those Protestant Christians who are actively engaged in Sunday services do so gladly and willingly and would not describe it as “work.”  

Although I am not in a position to comment on the Presbyterian view of the Sabbath, the Bible has this advice with regard to all who participate in Sunday worship and observation of the Sabbath:


  1 Corinthians 10:23-32: “Everything is permissible” – but not everything is beneficial.  “Everything is permissible” – but not everything is constructive.  Nobody should seek his own good, but the good of others...  For why should my freedom be judged by another’s conscience? If I take part in the meal with thankfulness, why am I denounced because of something I thank God for?  So whether you eat or drink or whatever you do, do it all for the glory of God.  Do not cause anyone to stumble, whether Jews, Greeks or the church of God – even as I try to please everybody in every way.  For I am not seeking my own good but the good of many, so that they may be saved.” 
  
  Colossians 2:13: “Therefore do not let anyone judge you by what you eat or drink, or with regard to a religious festival, a New Moon celebration or a Sabbath day.”