The largest number on the horizontal axis, in the run length plot. Or, the largest value of t on the plot for which P(RL=t) is plotted. For example, selecting 500 will give a probability plot of run-lengths in the range 1,2,...,500.
Quality, quality, quality: never waver from it, even when you don't see how you can afford to keep it up. When you compromise, you become a commodity and then you die.