No, Not every lock can be opened with the same key.
This metaphor means that not every child can be raised the same way. Every child has different needs. If all parents attend a parenting class all kids will be the exact same since they've been raised the same way. It also takes a lot of money and ti... me. If you spend a lot of time at classes, You'll miss out on a lot of time which can be spent with your child. It's too expensive