What are the most effective methods for structuring a training schedule to achieve a balance between intense interval training, endurance rides, and recovery periods, while also allowing for flexibility and adjustments as needed? Are there any specific training planning tools or software that can help cyclists organize and optimize their training schedule, and what features should they look for in these tools? How can cyclists ensure that their training schedule is aligned with their specific goals and objectives, whether its preparing for a competitive event or simply improving overall fitness and performance? Are there any general guidelines or principles for determining the optimal duration and frequency of training sessions, and how can cyclists avoid overtraining and prevent burnout?