CrossFit Endurance classes have two main priorities.
First, to teach and instill proper form. All to often people pick up running as a sport, be if for their first 5k, or obstacle course race, and start training without a thought as to technique. And why should they? They have been running since they were kids. Yet since we were kids we’ve been learning bad habits, some caused by improper footwear, some caused by improper mechanics. Learning proper technique will improve your performance and decrease injuries.
Second, to increase power and speed through high intensity interval training. This decreases high volume training loads, which in turn reduces overuse injuries and reduces loss of lean muscle mass.