154.2200 MHz is a SYNCHRONOUS SIMULCAST system. What all this means is that multiple base stations, each at a different location, transmit the same information at the same time. The result is a net improvement in coverage. But there is a tradeoff. What is frequently heard is phase distortion as a result of multiple overlaps or from multipath (reflections) from various ground formations and construction. There can be deep and rapid fades as the signals cancel out (remember addition and subtraction of sinusoidal waveforms in geometry?). If one of the sites goes out of lock, you can also hear heterodyne, which is generally more destructive.
Synchronous simulcast is less noticeable in a digital domain where machines, not the human ear, contend with the multipath and phasing errors. In analog it's a tradeoff to "better" coverage.
Note that these systems are ENGINEERED to blanket a specific area with signal, in this case the Central County E9-1-1 catchment area... there is no compelling reason to cover a greater area and to do so effects the economy of the system. The overlaps within this specified area can be adjusted within reason, the fewer the better. If you are on the periphery or outside the intended area of coverage, the overlaps would not be optimized and reception would be poor quality, even though theoretical signal levels should be higher.