There is simple rule. "BEYOND plays Cue. BEYOND does not play Zone".
Logic behind is simple. Every time as you start cue in the grid, BEYOND create cue player. It is one single player, that serve one single cue. Play can be pauses, restarted and so on, because time is one of player properties. And, frames calculated by player goes to the output - projection zones. Projection zone is a destination, and it can be dynamically changed (zone chase effect, and so on). So, projection zone is at the end of pipeline.
There are some exceptions from this logic, but is goes out of scope of initial question.