What are some potential ways TrainerRoads adaptive training could be applied to improve the consistency and sustainability of high-intensity efforts over the course of a long season, and how might this change the overall shape of a training plan or the mix of workouts and recovery days, especially with respect to balancing short-term gains against the need for long-term durability and resistance to burnout or overreaching? Are there opportunities to use adaptive training to personalize and fine-tune the sweet spot or tempo zone, and if so, what benefits or drawbacks might be associated with doing so, particularly for athletes with varying levels of experience, fitness, or goals?