Queue Prioritization - How Does It Work?

[KisaiTenshi]

This seems to suggest to me that for the past almost-hour there have never been enough people queued for Trial Roulette to fill an 8-man instsnce. That seems impossible to me.

This is only true at like, 2am. Typically roulette trials at least for healers and tanks aren't very long, and Cape Westwind comes up fairly frequently. The trial queue is the fastest queue to do, so it is technically possible that there's some other content players are playing instead (eg HoH) that is resulting in low participation.