I'm no expert, but my understanding is that SES still has a very long way to go.

Auditors: 'Single European Sky' failed to meet main objectives

"The auditors noted that there was "no substantial defragmentation" of airspace management. As a result, each time a plane enters the airspace of a member state, it is serviced by a different air navigation provider (ANSP) on the basis of different rules and requirements, with extra costs and time.
This, the auditors said, was due to a "lack of commitment on the part of the member states", which want to "preserve sovereignty, the legacy of national air navigation service providers", revenues and workforce."

And so on, and so on.

1964 - AMS-CPH: block time 1h20. Aircraft: Lockheed Electra II, cruise speed 530 kph
2019 - AMS -CPH: block time 1h20. Aircraft: Boeing 737, cruise speed 907 kph

Johan