I guess everybody has the method that works best for them. So here is mine, 20 years, and 3 trailers, never a problem.
Dump black tank, flush hose with grey tank, hook up black tank flush (last 2 trailers) run for 5 -10 minutes, always suprising to see what comes out after several minutes of clear water.
Add 2-3 gallons of water to both tanks, throw in small hand full of Borax or White King D and a small amout of Calgon and drive home.
Never had an odor or compaction problem so I ain't changing anything!!
Tinbender