It took you 50 times as long to write that reply than it takes to do a performance calc. That’s all nice what you wrote and I agree, I have gross error figures in my mind for many different conditions and weights so that I can pick up something that is ‘off’. Problem is though that Airbus says a performance calculation should be completed for every landing, so the real question is, if the book says to do it, so why not just do it? And if you happily ignore that Procedure, what procedures in addition to this are you happy to ignore? As a sim instructor I also know what figures I can chuck into the box to get us going for a multitude of different conditions, would you be also happy for me to use my own figures for takeoff as what is the point of the perf calc if I know what will work.