They are probably looking at Sunday readings. Only 20% of practicing Catholics go to daily mass.
The Lectionary would, for example, take the faithful through St. Matthew chapter 3, verses 1-6 on one Sunday, skip verses 7-11, and continue on the next Sunday with verses 12-20. This example is fabricated (for) the purposes of illustrationYeeesh! A real example would be nice.
Okay, now I see that the author is talking about the weekly readings only.