Fucking nightmare.
Some parents looked at practice as free day care. I had one set of parents who were always late picking their kids up from practice/games and I could not leave their kids alone.
Another parent dropped her kid off, and that kid always had to go to take a dump 10 minutes into practice and the nearest bathroom was at the library about 1.5 miles away. I had to stop practice, drive the kid to the shithouse, wait, and then drive him back, losing about 1/2 hour of practice. I always took a couple of his friends with him so I wouldn't be accused of being alone with the little shitter.
One year. That was it.