I've had one form of the 11" MBA since they came out and have never had to use the extension cord on the power brick. I think they are all still wrapped in Apple packaging. Try a few trips without the extension and you may just be surprised at how easy it is to loose. That and great battery life mean it only has to be plugged in at night or during lunch breaks. I frequently take trips of 3-4 days and never have to unravel the MagSafe cord other than the ~12" or so I leave dangling. YRMV