How do you think that life will change if we'd have a shorter childhood?

Let’s say 10 years instead of 20(I think that we all agree that 18 isn’t the time when you become mature,maybe 20 isn’t either but that’s when real life begins).So what would happen if you you’d finish elementary studies at 10,become sexual mature,go to college etc.Would our life be better?will it seem longer? etc