Are the shorter Zwift races like the Crit City and Sprint events, which are typically under an hour, really the most effective for interval training, or are the longer events like the Tour of Watopia and the Mountain Route more beneficial for building endurance and mental toughness. Some argue that the shorter events allow for more focused interval sessions with less downtime, while others claim that the longer events provide a more realistic simulation of real-world racing and allow for more varied interval training. What are the most effective Zwift races for interval training, and how do you incorporate them into your training plan.