Park visits have always been age dependent for me too. Or if I've had that "one" kid who just can't be trusted. This year I have two almost two year olds and two girls heading off to school this fall and park visits have been going fairly well although they never are more than 30-45 mins because it does get stressful always keeping track and making sure no one is doing something they should t be doing.

I wouldn't say anything to the parents because like someone mentioned, you may want to give it another go later on. With 7 kids though it's no wonder it was stressful, I wouldn't be able to do it with that many!