In the past I had issues with the gauges accuracy. Since I started doing the above I haven't had any problems. I heard on another thread that using automatic dishwasher detergent in the grey tank is a good idea. I probably will try that as a once a year cleaning method.
2004 Chevrolet Silverado 3500 LT with a 2004 Jayco JayFlight 29BHS
2014 Greyhawk 31FS with a 2007 Tahoe toad
2014 Thor Palazzo 33.3 with a 2007 Tahoe toad
I usually follow the same procedure for cleaning my tank. I saw an article somewhere saying that adding a certain amount of Dawn dishwashing detergent to black tank after emptying, and adding a few gallons of water really helps keep the tanks clean. I can vouch that it is far better than the blue stuff. I add about 6 ounces.