Same here. Sometimes I wonder if it doesn’t detect the slowest of leaks though; the kind that won’t drain your co2 tank, but will make the beer take twice as long to carbonate.
I only have 1 spare keg to my 4 on tap. When I kill a keg, I pull it out of the fridge and let it sit under pressure until I am ready to refill it. I will clean and sanitize right before filling.
That’s pretty much how I do it. Then I clean a few at a time. Sometimes I store them pressurized, sometimes not. They get sanitized again before they get filled either way.
I keep a couple new keg lids, some extra pressure relief valves, lid feet caps, and extra o-rings on hand. And when I have a problem lid it goes into the “Use as last resort” bag – gets swapped out. And when I find a problem (crease, nick, bend) along the rim of the keg opening, I have done my best to bend it back to the desired shape. The theory is to remove all the defective parts within my inventory (around 22 kegs) so that when one is brought into use I don’t have any that leak.
I don’t think that I have any ball lock kegs that require a specific lid. I do carefully seat the lids, sometimes having to reverse the direction the lid sits to get the best seal. And spray star san when setting the lid under pressure to check for leaks.