There is a myth that pressure switches are unreliable and/or subject to failure. We've actually never seen a failed pressure switch, but we've seen plenty of failures in applications or mis-uses.
1. Using without a relay. Honeywell specifies 10A resistive load capability. Not motor load. Some mistake this as suitable for running a small fuel pump that draws less than 10A. The problem is that a motor has inrush current that destroys the internal contacts. The appropriate use would be to use the pressure switch to energize the coils of a relay, and to let the relay take the motor's load.
2. Using on the wrong application. In automotive use, the most common configuration is normally open (off without any pressure) and on (closed) at 4 or 5 psi. Depending on the primary pump size and the fuel requirements of the motor, the primary pump could simply run out of capacity before the closing pressure of 4 or 5 psi. In this type of case, a 4-5 psi pressure switch is simply not the right type of logic. (instead, look at a vacuum switch, rpm switch, aux output from boost/nitrous controller, etc.)
3. Mounting where it is exposed to vibration. You cannot mount a pressure switch directly on the engine, supercharger, head unit, intake, or anywhere rigid. Vibrations will cause the pressure switch to disengage under boost. The best practice is to mount to a vibration isolated boost/vac manifold, or simply zip-tie under a wire loom.