I had a layover in Copenhagen on my way to Amsterdam in May, 2016
As soon as the plane landed and we got out of the airport, we got on the first train for the city. It was still early morning, not even 8 am yet, our plane for Amsterdam left at 1 pm. That gave us plenty of time.
We were on our way to Copenhagen for breakfast, a five hour layover between planes on our way to Amsterdam. Why wait at the airport when the city is only 15 minutes away by train or metro.