Right now, Garmin Connect created power based workouts on the road with a power meter are useless. Unfortunately the vast majority of power meters give a very high power fluctuation on a second to second basis. When you pedal on the flat at quite high intensity, at one moment the power reading is 200 W, the next 400 W, then 300 W, even trying to pedal as smooth and regular as possible. This is inherent to power meters and happens regardless of brand and positioning of the meter, whether on the pedals or wheel hub or elsewhere. If you try a power based, Garmin Connect created workout, you only get a beeping Garmin all the time showing that your power is either too low or too high. This even using a very large window of power, like 240 to 300 W.
With (for example) Edge 500 you could create or edit workouts on the watch and change workout (one second) power to P3 or P10 or even P30 (respectively 3, 10 or 30 s average power). That would smooth power readings and make power based intervals feasible and a very powerful & useful training tool.
With Edge 520 and others you can't create or edit workouts, you have to create them on Connect and download them without editing. PLEASE add the option of using P3 or P10 or even P30 INSTEAD of 1-second power to the Garmin Connect Workout creator.
After all, many cyclists and triathletes choose not to have 1 s power shown at all on their Garmin, opting for P3 or even P10 instead. Heart rate and speed/pace fluctuate much, much less than instantaneous power.
