Here is another interesting video from Mike Busch, just off the press
https://youtu.be/qg89aV1buDc
I was listening discussion the other day between business owners comparing efficiencies between their 3 pilots.
At the top was the most experienced pilot whose fuel consumption was at minimum for the same route. His tracks were consistent sharp straight lines.
I would be analysing past flights of more experienced colleagues, cross checking speed/altitude with winds.