I guess you could, but since it was designed for me, I'd have to ask the guy who designed it. I don't see why not.
I will tell you that I get very little air leakage. I have a silent compressor with air tank and automatic on off switch. When I have the compressor on and am not using the brushes, the compressor doesn't kick on very often to refill the tank, meaning I am losing little air. You still would shut the air off at the tank when not in use, just as I shut my compressor off when I am not airbrushing, but as long as you do a good job with thread tape and tightening the fittings, I don't think you would lose much air from your tank while you had your main valve open.