If I know the system and the zones are fairly small, sure, I can do more than 3 zones. You can always try it and shut down zones as needed. We try and not even communicate with the client when we are there for the service. We open the zones manually thru the bleeder or solenoid. If the valve is a known problem, meaning it won't shut down manually, we have battery operated actuators. Most resi systems here have the manifold in on or two places. Not the multiple alves throughout the yard.
Guys, this is not rocket science. If it was I'd better be making a lot more $$$. Go to your local rental shop, even if you are planning to buy a compressor (who knows, maybe they have one for sale. Quite often they do), and ask them what most companies use. Have them show you the different sizes, how to adjust the pressure, the hoses, hook ups. if you rent and it doesn't meet your needs, take it back. Get a larger or smaller compressor. Get one to make it quick, easy and efficient.
AND WEAR EAR PROTECTION WHEN DOING BLOWOUTS!!!!
The compressors have a ball valve at the point where you hook the hoses up. I also have a ball valve at the end of the hose where I hook to the PVB, RP, manifold or where ever. I'll post a pic of my set up for attaching the the POC.