Ah, that is very interesting... By following this "three-year cycle for Sunday readings", is the entire bible eventually read to the church members?
The coverage is extensive, but you'd have to go every day, and even then there just aren't enough days to cover every single verse using the one-topic-per-reading format. There is an OT reading, Psalms are sung, and a Gospel reading every day, and another NT reading (usually from the epistles) on Sundays and Holy Days.
I suspect the extensive schedule of readings carries over from times before printing presses and and education of the lower classes. For most of the church's history the only way most in the congregation could learn the Bible stories was by hearing them read.
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@FHN: we also have what are called Catholic "CEOs": Christmas and Easter Only!