I have an Ingersol compressor. It says expressly in the manual "not to turn it off when running" by any means. I have a ballcock shut-off that isolates the line from the compressor so I can shut off the air supply, but the compressor can keep running until the tank is full. Then it shuts off on its own. It's always on and ready to go, just need to turn the ballcock on.
i had a silentaire 20 a compressor for 6 or so yrs. fine machine, nothing better. bought a new one due to needing more tank capacity. made in italy no less. wouldn,t have anything else. they,ll last about 25 yrs. or so with proper maintenance.