It doesn't matter what procedures anybody uses, as long as the performance is CALCULATED and makes logical sence! Take for example V1. I've seen it so often in Firenze (for those who've been there, I don't need to draw a picture), where some captains take their hand of the thrust levers long before V1 because their feeling says they won't be able to stop anymore. Yet they've never actually ever stopped and measured the distance before in reality. I understand performance can be quite critical at times, but it does work, otherwise aircraft would not be certificated. Airbus is working on a system that calculates, compares and displays your required acceleration against actual accelleration in real time. Should be pretty cool...