Some of the tank cleansing rituals used on these boards are great morning reading material while I sit and dump.
Personally I dump when I leave a campground be it 1/4 full or 3/4 full. About the only time I use the almost worthless tank flush connection is at the end of the season as a tank filler to flush before I put the cover on for 4 months. I do not worry about if half a turd remains in the tank between trips.
Not long ago I watched a guys flushing ritual for about 45 minutes at a state park while his wife yelled multiple times from the truck window "make sure you get it all out Al".
Great entertainment is where you find it. I was literally 400 yards away up on a hill and this woman was like listening to nails on a chalkboard. She was worried about a turd being left in the tank and would have none of that foolishness, and she let Al know it. If I was Al I think I would have found the ranger and filed for divorce on the spot LOL.