What I've noticed is that kids who stay past 9 hours typically have worse behavior. I ask my parents to leave them no longer than 9.5 hours. That gives them 30 minutes for lunch and 30 minutes travel time each way.
Many times this has required that one parent drop off and one pick up.

I've also observed that parents who leave their kids 10+ hours are problems in other areas such as hot checks, leaving owing money, late to return required forms, etc.

Ocassionally I get a call for a newborn and mom wants to drove the baby at 6am and pick up at 6pm. I decline and suggest that's too many hours for any child to be away from their parents/siblings. I understand economic pressures, and at the risk of sounding rude, why have children if you can't spend time with them?

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