I typically wait until I have at least two kegs that need cleaning. I'll put PBW in one keg until I think its clean. Then I'll move it to the 2nd and put BLC in the 1st while the 2nd is soaking. I just do a gallon of BLC and run a good bit through each dirty line/faucet and let them sit for about 15 minutes and then flush the rest. Then I rinse both kegs with water and flush the lines with water again. I begin my sanitation process by mixing up some Star San in one of the kegs and then running enough of it through any lines/faucets that are currently unused but just enough to fill the lines. Then I remove all of my lids, ball locks, pop out the popit valves, and the CO2 in tube and boil them in water on the stove for 15 min and take the diptube and let it sit upside down in the rest of the Star San in the keg that is holding it. Reassemble everything, transfer Star San to the next keg, and fill the empty keg with whatever beer needs to be kegged. It's almost as long as a brew day but I'm confident that I'm not contaminating my beer. I'd love to hear any shortcuts that anyone else can suggest.