I have to weigh in on the Sullenberger case. I fly for the former US Airways, on the 320, and have flown with Sully. He abandoned the checklist all together because he knew that he could never get through it. I am looking at the A320 QRH, it has been amended since Jan of 2009, but "start the APU" is way down the second page of a two page procedure. Sully jumped right to that and the NTSB report lauded him for it.
Accident Report
NTSB/AAR-10/03
PB2010-910403
"Although the flight crew was only able to complete about one-third of the Engine Dual Failure checklist, immediately after the bird strike, the captain did accomplish one critical item that the flight crew did not reach in the checklist: starting the APU. Starting the APU early in the accident sequence proved to be critical because it improved the outcome of the ditching by ensuring that electrical power was available to the airplane. Further, if the captain had not started the APU, the airplane would not have remained in normal law mode. This critical step would not have been completed if the flight crew had simply followed the order of the items in the checklist."
The NTSB also noted that the checklist itself was not designed for the scenario of flight 1549:
1.17.1.2 US Airways Engine Dual Failure Checklist
According to Airbus, the Engine Dual Failure checklist was originally developed “based on the highest probability in time of exposure that a dual engine failure would occur.” Because Airbus airplanes spend much more time at higher altitudes and, therefore, a dual-engine failure had the highest probability of occurring at a high rather than a low altitude, Airbus designed the Engine Dual Failure checklist for the occurrence of a dual-engine failure above 20,000 feet. Airbus indicated that it had not considered developing a dual-engine failure checklist for use at a low altitude.
Sully, a former F-4 pilot, had the fighter pilot mentality and history of a lot of "Bold Face" memory items. When you are the only person in a really fast airplane that glides like a brick you will not have a lot of time to read stuff about what to do. You need to have the the major items memorized so you can do what you need to do while you "Aviate, Navigate and Communicate."
You don't allow the checklist to get in the way of that.