CrossFitters face one major problem in trying to develop correct strategy and pacing strategies.
They make the mistake of trying to use an energy system that’s too intense for the workout they’re doing. As a result, they reach a threshold and the byproducts of the energy system inhibit their ability to stay in that system, they ‘hit the wall’ and intensity (and therefore output) drops.
This looks like this, with an exponential increase of rate of perceived exertion (effort/pain) with an exponential decrease in output (round time):
What we're looking for, is a linear increase in rate of perceived exertion with a shallow inverted U of output (round time). Build intensity to maximum sustainable intensity, maintain that intensity, then cross the anaerobic threshold to take advantage of the higher output available in the anaerobic energy systems: