The advice about waiting until it is full before dumping was only half the story. The other half is to not leave the dump valve open on black tank or you will have problems. So, answer is, close black tank dump valve until you are ready to dump, be it after a 3 day weekend or whatever. Make sure there is plenty of water and dump away. Close valve when done until next time you want to dump.
If you want to see what happens when you leave your black tank dump valve open, proceed with caution and make sure you have plenty of time allowed for showering and clean after you unplug that mess. Had a friend not understand this and he left his black dump valve open, backed up one night when it was raining, I don't think he ever did get the stinky slinky cleaned out, I think he replaced it.. It was several days of messing with the mess and boy did it stink around their trailer...
It is a holding tank and if the valve is left open, eventually, the liquids drain out leaving solids. It depends on usage and the plumbing, but it will happen.
My wife and I camped in the front yard of a house one of our kids was buying, dumped at dump station on way home (only parked there 4 nights so tank not very full.