A bonus post today since part 4 was so short!
Speed training is done ONLY after the long slow distance (LSD) is completed.
Fartleks versus Intervals
Bromiley does describe some interval training (not as in depth as Tom Iver's books), however seems to favor Fartlek workouts. She states that some horses don't do well in interval training because they don't settle between the sets. Farleks are worked slowly over a longer distance, utlizing the "gait of their sport", with short periods of high speed activity. For endurance, this would mean walk/trot, with short periods of canter or gallop. They don't need to be of a uniform speed or distance. According to Bromiley, the Fartleks are easy to incorporate into a conditioning program, while the interval training concepts require a carefully calculated regime to be really effective.
Bromiley doesn't offer any hard and fast rules for recovery - just to read your horse and respond. Good advice!