It seems to me that there are more open threads than caucus, prayer and devotional threads combined. It also seems that caucus, prayer and devotional threads don't generally get as may replies as open threads. The qualifier, "by far," seems quite strange.
Examples:
Traditional Sunday Propers ~ Dominica Qvinqvagesimæ ~ Quinquagesima Sunday
Catholic Caucus: Sunday Mass Readings, 02-22-09, Seventh Sunday of Ordinary Time
Might be due to the weekend RM.