They seem to be because no one wants follow the rules. Really depends on the shift. Some operators follow the old zones, for example:
R-3 is where NW was at.
R-4 is where NC/NE was at.
R-2 is where W/S was at.
R-5 is for overflow or patches OOC. EMD only does EMD now, so the old North zone would be lumped in with R-2.
Each call is supposed to be rotated through to spread the workload evenly, but ya know how that goes. And say, for example, if Mount Laurel is on a call on R-3 early in the morning and they’re busy as usual, call after call, they’re probably never coming off that channel because you don’t want to split up the towns between two different channels unless necessary due to a significant incident, etc.