The 96 stride rate we suggest you run at in training is to ensure that each person, no matter who, focuses on increasing their stride rate during run training. As a rough estimate, I'd say about 90% of AG athletes neglect to focus on training stride rate, and most run well under 90 steps per leg per minute. 96 is not an arbitrary number and it is important to understand that this is a training target, intended to be followed consistently over time, in order to assist you in learning to run with a higher stride - but not necessarily always at 96! It's a great target to "aim" for in training because you can count it easily, and low to mid-90's is a good target for racing. In most cases, you will not be able to hold pace, rate or exertion levels late in a race as what you held in training sessions, but by race day you should have "programmed your red meat computer" to run at a higher stride rate. 96 is the target in training, you'll probably hit a little lower in racing, but because you have trained this way, it'll come more naturally and you will focus on it, rather than running at "any old" stride rate, which when we are tired and depleted tends towards "trudging aka the Ironman Shuffle." And besides - 96 divides by 6, 4, and 3, meaning you can easily track the consistency of your strides per leg per minute over 10, 15 or 20 seconds at a time (ie multiply strides per 10sec x 6 and you get your rate/minute).
Hope that helps. Happy running!