No racing about it. I don't get into a hurry either. It doesn't take long to dump the black and grey tanks and move on so the next person in line can do the same. The dump station isn't a part of our camping trips I like to hang around and relax for 45 minutes. Our current TT has a black tank flush connection. I haven't used that gimmick yet. Not going to waste my time or the people's time behind me in line at the dump station. If you think it cleans your black tank, you're wasting your own time as well. The best method for keeping your black tank flushed out is to use a lot of water when you flush the commode.
https://www.youtube.com/watch?v=dfTd0Slt_cU