Correct pacing strategies become even more important. Not just because of our knowledge of the energy systems and their role in energy production (and eventually, physical output), but also because our effort impacts our psychology, and our psychology impacts our output. And ultimately, we can increase our performance.
Much importance is placed on the success of each individual training session an athlete completes. Although the sum of these individual session is important, sometimes the emphasis placed on this 'micro view' of progress can be damaging.