What are some of the most effective ways to structure group intervals on Zwift to maximize both the social aspect and individual training benefits, and how can ride leaders balance the needs of riders with varying fitness levels and goals, while also ensuring that the workout remains engaging and challenging for everyone involved? Can Zwifts features, such as Meetups and Events, be leveraged to create a more dynamic and immersive experience for group intervals, and what role do you think virtual training platforms will play in the future of cycling training and socialization? How can riders and ride leaders work together to create a supportive and motivating environment that encourages participation and progression, particularly for those who may be new to interval training or group rides? Are there any best practices or guidelines for communicating effectively during group intervals, and how can riders provide constructive feedback and support to help each other improve their performance and reach their goals?