What are some key considerations when structuring a Zwift workout plan to maximize progress in a specific racing discipline, taking into account the nuances of virtual training and the unique demands of different events? For example, how does one balance the need for interval training with the necessity of longer, steady-state rides, and what role should strength training and recovery days play in the overall plan? Are there any specific Zwift workouts or features that are particularly well-suited to preparing for certain types of events, such as hill climbs or criteriums? How do experienced Zwift users adjust their training plans as they approach a key event or racing season, and what are some common pitfalls to avoid when using the platform to prepare for competition?