You only save CO2 if you have a leak, and not keeping the gas connected is a way to avoid that problem, not solve it. Moving the tank 4', connecting a disconnect or re-attaching the regulator, opening the fridge so you can connect everything and losing the cold air, that sounds like a bunch of work to me. Especially if you have people over and you'd need to do that every couple minutes across multiple kegs. I agree, to each his own, but I fail to see any logic in your methods. I could maybe understand if you were just doing this while carbing (and didn't have enough gas lines/ports, or one keg was carbing at room temp, etc.) but certainly not serving.