IMO it's in the best interest of the kids to have as much of a consistent/united front in parenting - but there are definitely frustration points. It's a lot harder to say "you have to go to swim lessons" or "you can't eat candy before dinner" or "you have to do your school assignments to avoid the Summer slide" when they don't hear the same message on the other side.
At +12yrs after divorce, this causes me minimal frustration. You and your ex may encourage an overarching code of ethics, but your S7 already doubtless follow different rules when attending church or school than they do on the playground with friends. As long as you're respectful of your ex's rules when they're at you're ex's, and your ex is respectful of your rules when they're at your place, that's usually enough barring abuse or neglect. My simple refrain is the following: "You follow mom's rules at mom's place and dad's rules at home." D3 I could see being more difficult. That's young for such variation!
Often we create rules because it's what we learned growing up or we believe we need to encourage good behavior. Your ex allowing candy before dinner is a perfect example. When your kids eat a few M&Ms before dinner at your ex's, does chaos ensure--e.g., they eat only half their food and skip their vegetables? Maybe the rule isn't needed. Every kid's different. I sometimes try dropping a rule and see what happens. If it doesn't work out I add it back and explain why.
