I have a portable compressor- one of the ones Machine Mart sells (or sold about 8 years back, I expect the still sell similar models). It has a storage tank etc and does all I need. (The air pumps on garage forecourts are limited to (something like) 60psi and I need 80 for our motorhome.) I use it now and then, just to top up the tyres on our vehicles, the trailer, and the odd air tool.
My concern is, it is rather loud and, while I don't use it often and I'm always careful about when I use it etc, it seems wasteful (for want of a better word) in terms of noise, to bring it up to pressure, top up all the tyres etc, and then empty it (including the 'drain valve'). I've noticed, having got to pressure, typically, it will start up once during use for perhaps a minute, maybe two. While I check my tyres far more often, they only need topping up perhaps twice a year, three at most.
Would it be safe to leave the compressor pressurised between uses?