I am not so sure I would agree with your statement.
When I started I flew a lot with the FD until one day I decided to fly raw data because the TRI I was flying with did one on the previous sector. Shambles
Scanning has to be practised regularly. And I do it quite often now, sometimes from above FL100 if the overall workload and airspace allows, and my overall confidence in handling the aircraft in a multi-crew environment increased a lot.