CI 10 and Traffic Flow
CI 10 is one measure to safe cost on the flight mission from A to B. As we are part of a complex traffic flow with different companies flying at different CIs, flow problems will therefore mainly occur on arrival routes of big airports. That is daily business and as such occasionally leads to more fuel flow due to more track miles. Proactive early questioning of required arrival speeds might prevent once in a while more track miles by speeding up or even slowing more down due to early arrival. Use flap 3 (where appropriate) and ask for a visual (where appropriate), perform a single engine taxi-in (where appropriate) and don't forget to switch Pack 2 OFF after landing and you might end up for the perfect day regarding fuel burn...
Most likely, we don't achive alll this on one single rotation, yet optimizing it to the best extent for every leg we fly is a great challenge and worth to try.