It depends. Sometimes I think issues need to be addressed then and there, otherwise one parents makes a decision and then later the rules change for no apparent reason. If you have a valid, logical reason for disagreeing and can present it respectfully I can't see it as a problem. If you start attacking the other parent or belittling etc then it is always going to be bad. Big issues/rule changes we tend to discuss beforehand when possible to avoid chopping and changing what we say.