The reality is that the slower cost index they've been throwing at us lately does not add a whole ton on to the duration of the flight. Last night on my redeye from SFO to JFK, we messed around with a bunch of different numbers and the slower ones added just a few minutes onto the ETE, and that was going all the way across the country. We were already using pretty slow numbers to begin with so it's not a massive change. It's not going to cause us to show up 20 minutes late or anything.
However, when you add up very small fuel savings times all the flights we do in a year, and it does add up over time. Just like the APU campaign going on. Few gallons here, few gallons there but multiply that by a large scale operation over time and pretty soon you're talking about real money.