And then remember that performance data is only "hard" (whatever that term means) data for wet and dry runway, for everything else it is only advisory information.
Performance data work on a perfect day, with a perfect aircraft and a perfect runway. Introduce rubber deposits on the opposite end, very worn brakes and tires, still warm brakes from a short turnaround, a fatigued crew and overweight passengers and you will be hard pressed to deliver the same results. Better build in some fat, for example calculating an intersection T/O, shortening the TODA in the performance program or add a ton to your weight.
And then you still can derate and assume as well as use improved climb V-speeds which will reduce engine wear a lot.