There are three types of workouts listed in the past performance records of horses: breezing (B), handily (H) and driving (D). Breezing means the horse was under no pressure at all and was not running near top speed. Handily means the horse worked eagerly with little urging by the exercise rider. A driving workout is rare as it is not often a horse is urged to go all out in the morning.
Workout times can be deceptive and usually do not reflect the true abilities of a horse. How much, or how little, a horse was urged during a workout is not only subjective but dependent upon additional factors. Was the workout made from a standing start? Was the horse galloping when it reached the point from which it was timed? Did the clocker time the correct horse?
The intention of a trainer is a guessing game and breezing and handily are not very descriptive terms. They alone cannot fully explain the ease or effort a horse put in during a workout, and thus comparing the times between horses, even if both workouts are listed as having been performed handily, is virtually meaningless.
The key to understanding workouts is the realization that frequency is the only compelling handicapping factor that can be derived from them. They are an indicator that a horse is likely not injured; that the horse is ready for a race. However, if a horse has not raced in several months, and only one track-mandated workout is listed in its past performance record between that race and now, I would see that as a negative sign. An absence of workouts over a prolonged period can indicate that a horse has a physical issue that required rest as most trainers with a sound, healthy horse will give their charge a workout or two to keep them sharp while they find it a suitable race.